I'm a very novice bitcoin user, so apologies for the stupid question.

I have a few wallets on my phone, each of which provided a backup seed phrase.  Two questions:

1) If my phone were to explode and I needed to restore my wallet, do I need to use the same wallet?  Or can a seed phrase I got from mycelium be used in electrum if I wanted? 

2) Is there no risk of people just randomly entering 12 word seed phrases in the hopes or recovering an active wallet with funds in it? 

Thanks!