ar-15 california legal magazine catch: What you are most likely looking for here, is a fixed magazine kit. Try searching with those terms, and you'll find one. The most popular one out there at the moment are the "prince 50" kits - there are two different ones; one is a bullet button and the other is a fixed magazine kit.
california legal ak 22: I don't think there are any 22LR AK's on the California assault weapon list. You're probably asking about the Romanian trainer, which is a 22LR AK, or the Armscorp AK-22. Both are entirely California legal, however it is worthwhile to note that the Armscorp product is only shaped like an AK-47.
wilson tactical lower receiver stripped ca legal: Yes, the Wilson Tactical lower is legal. The Wilson Combat lower (produced by the father of the guy making the Tactical lowers) is listed and hence illegal.
automatic shotgun magazine conversion: In California, a detachable magazine on a semi-auto shotgun is an assault weapon. Don't go there if you're in CA. Otherwise, enjoy! Of course, if you mean fully automatic, that's federally prohibited. On a side note, the Saiga-12 is California-legal if you use a fixed magazine system.
building an ak-47 using ewbanks receiver: It's more or less the same as building an AK-47 using another standard stamped receiver.
is it legal to have forward pistol grip on ar: In California? Yes, provided that you have fixed a 10 round magazine in place on the rifle or your rifle is rimfire (i.e. 22LR or 17HMR2), or your rifle is non semi automatic (i.e. disabled gas system).
mini14 still legal in california: Yes. Just don't install a side-folding stock or other SB23-prohibited features on it.