Siamese fighters differ greatly in temperament. I've had some that were really violent, my worst is actually a female who loves disembowelling guppies and now has to live in a 'breeding net' to protect the other fish in the tank, but most are fine. Some males just can't be kept with other long finned fish but most will only nip every so often if at all and if you keep them with reasonably tough fish and don't mind slightly nipped fins they're fine. Guppies are perfect for keeping with fighters, I do without any problems (with the exception of my grumpy female, Scelesta).
What you really need to watch is other fish nipping the fighter's fins. Any fish that have even slightly aggressive tendencies will find those long trailing fins irresistable and will tear them to shreds. If the worst comes to the worst, spend $5 to $10 on a large breeding net and keep them in that. Be aware that some have a tendency to jump so be careful with anything without a lid.
I don't know about angels, I don't have any.