Two questions.

[Rill]

First of all, is base attack worth investing upgrades into at all? It seems like the extra attack value far outstrips it in damage.

Second of all what exactly does foundation do? Does it increase the level where you second tribulation, or does it increase the stats gained from the second tribulation?

[Mad Hawaiian]

Foundation does several things, it is worth it to always try for double foundation before advancing. You can open your menu and highlight the bottom left area to see the effects of foundation.