Excellent guidelines, HenrikE !!!
Thanks a million...your guidelines was helping me to crank up my good old A500 w/ Omni 4.4.4-20150210. :D:D:D
GApps link in the OP is dead...may be you can update it w/ the latest one from here:
Skrilax CZ V9
TWRP v 2.1.3 (Primary recovery)
TWRP v 220.127.116.11 (2nd recovery)
Omni 18.104.22.16850210 (CM-11)
Thanks a million to everyone, who keep maintaining & contributing to this great XDA-Dev board...!!!