1) Good, will gladly test this tweak!
2) I mean placement only at the start of the game. So like you place buildings - place Towers near them (closer to Core if possible), so people would be able to grind some resourses automatically.
For example - with current upgrades i can:
build 4 towers initialy and (i think) get to around 12-15 wave, for which i get around 300-500 Gold and Wood and some other resourses (depends on placement of everything) - for auto and this might ensure i can start runs with 2-3 first buildings and crates, so additional Iron will come only every 2nd-3rd run.
build up to 5 towers, 2 Relays and get to 20 wave, for which i can get around 600-700 Gold and Wood + some more other - for manual play.
3) That's why i am saying about button. Do you tell us there are useless upgrades? ;) I am sure there will be a point where you might want to just spend without searching for the cheaper upgrades.
EDIT:
4) Forgot one more thing - the statistics or some kind of encyclopedia with at least base stats (for now) for relevant things - orks, towers, buildings.