Xander! He will only appear in the Recruit screen for those with a Premium Content code. (Details at the bottom of my post.) Xander is a reserved British guitarist, written mostly by Serenity Frost. His story isn't as long as the other romanceable guys, which is why I consider him a bonus character, but he still has a good amount of content. His route includes a potential alternative outfit for himself and for Robin.
So my hints about the ending were too subtle, so you should get 3 scenes now of the band members dealing with their conflicts and Robin noticing, even if you're not on their romance path. Spoilers for those scenes: Dallas' is pretty much the same as his romance path - you go to the pier, but you don't dance for him (you have to "hang out" after the AMP nomination). Emmitt will now get a cutscene when you go to band meeting and, depending on your relationship with him, he'll say different things in a band chat afterwards. There's a romance version, friendship version (75%+ affection) and not friends version. Subsequently, all the previous "hint" scenes have been adjusted to only happen after you've been nominated for an award, so the timing is more appropriate. Beau's scene is Robin walking in a band meeting where she wasn't invited, Beau reassures her it was nothing to worry about and she believes him.
Some Open Mode characters now have their own song flavor (unique song titles and themes) when they're writing music, just as Robin/Dallas/Beau/Emmitt had in Story Mode. Wizz and Rose's songs will have geeky names, for example. Alessandro will almost always write love songs, Emma about the government, and such. This should be good for customizing your band further. If you wanted to make a Christian rock band, have Claudette write all of your songs. If you want an emo flair, go with Seth. Some characters don't have any unique flavor, which allows for more variety (won't see the same songs over and over).
Stage effects are now something you can see in action! A long, long time ago, I had full screen effects for these items that happened when you matched their tile in the gig minigame. They were distracting and lagged, so I took them out. Only a sound effect can be heard when you match these tiles now. So the coolness of buying these effects was lost, but hopefully they're cool again! Woo!
There is now a "manage equipment" button on the Modify Band page where you can turn the effects off if you don't like them (but you keep the stat bonuses). My favorite part is you can change the color of the lights and lasers! 
The footlights & big screen, previously obtained when purchasing pyrotechnics, are now unlocked by playing the theater and arena venue. So you'll get them eventually over time.
Introducing: the Band Snapshot tool! Make a record of your band so you can share it with others (like me! I wanna see!) On the screen are several stats tied to your current band and slots that you can toggle to show more information of your choice. You can show your top CDs, cover designs, how many Gold/Platinum albums you have or your favorite song. (The control GUI for that disappear when you take the actual screenshot so it looks pretty.)
This screen will now appear automatically at the end of Story Mode's credits, so if you've won an AMP, it will appear.
Boosted CD sales is something I've wanted to do for a long time. In the real world, going on tour is usually meant to promote a specific album. So now you are encouraged to play your recently released songs at gigs. If your CD is at 25% popularity or higher, playing a gig will boost its sales for that day (amount depending on the venue and % of popularity left). In the beginning, playing at bars may sell 5 extra copies of your CD, but this number will be in the thousands during late game. It will add up come time for your paycheck.
The graphic shows all CDs that the current setlist is playing off of, but CDs that won't be boosted are faded out. How much your CD will be boosted will be represented by blinking arrows on top of the CD. 3 upward arrows is the highest.
There's been a large update to the number of houses/bases for your band in the Realtor screen. I added ten new bases in total, five for Premium Content owners only. When your backgrounds are photos, you can do this. 
They all cost a different amount and are sorted between the tiers of stress bonuses. I know that I did not need to do this at all, but I did it anyway. Yes, I'm sorry that I did this and not write Seth. I'M SORRY OKAY I JUST LIKE INTERIOR DESIGN.
You can now preview a base's BGs before signing the lease. The BGs you will see most often are the last two (band meeting space and the BG behind your daily planner). But of course, any story scene that shows Robin at home will change to match the base theme as well (BGs not shown are her kitchen, exterior night shot, and bed.)
The new bases are:
- Punk House - Based off of community squats in the punk scene (but you have it to yourself)
- Bohemian Hovel (Premium) - Free-spirited design in a country hovel
- Cute Apartment - Cutesy and colorful, if your Robin likes that
- Occult House (Premium) - Maybe Robin is a Wiccan and/or loves Halloween?
- Retro Home - A quiet and comfortable home stuck in the past
- Suburban House - Named the "Hamptons" in all the files, but real places don't exist in RR
- Village Home (Premium) - European house
- Ranch (Premium) - exactly what it sounds like, live like on a farm
- Beach House (Premium) - Colorful and full of green
- Pink Paradise - Very chic and luxurious, also pink
If you'd like a Premium Content code, I'm not a stickler. You can email me (maselphie @ gmail) with your band snapshot/your favorite character route and I'll give you one. (Fanart/fiction also accepted!) If you hate human interaction, you can just donate to our future projects and get one off of the itch.io page. 
I think I'm done adding content to the premium code, so this is it. I'm finally happy with it finally being worthy of the donors.