As this effect only affects creatures, one easy way around this is to primarily use card types such as artifacts and Planeswalkers that are capable of targeting your opponents' permanents, rather than using creatures that can be more easily removed than ever
If multiple cards leave your graveyard at the same time, Teval's Judgment's ability will trigger only once
Legality depends on the tournament format -- Reanimate can be legal in some formats and banned or restricted in others
It enters untapped as long as you control a swamp, producing black mana when needed and drawing cards when youre ready to pay the price
It's not surprising they've held their value
I received an email from the art director, Dawn Murin, in November 2018, about 4-5 months before the project was due, which is very unusual, and about double (or triple) the normal span of a project timeline for Magic