1. There's only the (slim) possibility of two different species of fish hybridising if they're in the same genus or otherwise closely linked genetically. In theory guppies and mollies can hybridise, they're both in the genus Poecilia, but the only known records of the two having fry, those fry have been sickly, weak and died. Other fish hybridise well like some cichlids, even some species of betta (there's more than just the betta splenden!) it varies fish to fish.
2. This depends on the individual bettas personality and what you're trying to put it with. Bettas do best with non-colourful bottom dwellers like corys, anything non-aggressive and non-territorial. But some bettas just won't tolerate anything while some are very mild. It just depends. I've had bettas with corys, dwarf corys, otos, large amano shrimp and even endlers livebearers (although wouldn't recommend that with anything but the most meek of bettas).
There are no published studies regarding betta fish memory at this point in time
Betta are social fish. There is nothing wrong.
sleep
Yes a betta fish will grow back lost scales with time and clean water.
They might mate on there own give them time but don't leave them together. One might kill the other and maybe the mother might start to fight back ,but in that case don't leave them together!
a long time
1 betta year is 20 human years ruoghly, 2 betta years is 40 human years 3 betta years 60 human years 4 successful betta years=80 in human...got it
No, you should never keep a male and female betta fish together for long time periods. They should only be put in the same tank for breeding purposes and then separated after.
no
That depends on the Betta fish. If it's just a bit of a nuisance, Some time in it a separate container could stop this problem. But if your betta is so aggressive, so hostile, it seriously injures the other fish in the community, than you have no choice but to buy an Breeder Box and keep the betta in there. Or buy a separate tank for the betta entirely. A Fightn' Fish Fact: Female Betta fish can be aggressive too. It's just less likely.
Bettas can die at any time.
i have had this happen lots of times whether your feeding them or not... it scares me every time... and it is with different betta fish so i think it is normal!