MTG Salvation

Hi, guys. I've been playing MTG for a little over a year and I've always played casually. My fiance and I are looking into building commander decks and we were hoping for some pointers as far as what a good commander to use. I'm considering using Progenitus as mine but this could be badly misguided.

Okay, thanks!

So even if their creature comes to the battlefield under my control, it will go to their graveyard when it dies while it's under my control?

Okay, so I have a zombie deck that has Grave Betrayal in it. I have several cards in my deck that return zombie cards from the graveyard to the battlefield/my hand. My question is when an opponents creature dies and it comes to the battlefield under my control and then that creature dies while under my control, does it go to my graveyard or back to theirs?

If a player puts an emblem on me with a planeswalker such as Ob Nixilis Reignited and then that player dies, do I still have the emblem or does it disappear from the game along with everyone else that belongs to that player?

This is possibly a stupid question but when artifacts say "Equip only as a sorcery" does that mean the equipment only stays on the creature until the end of the turn in the same way that A sorcery card is only effective for one turn or does it just mean that you can only equip it when you could cast a sorcery?

I have a question regarding Aetherflux Reservoir. Can I use the card as basically a suicide bomb card? Can I pay the 50 life to kill another person I'm playing with even if I don't have 50 life? Can I just kill both of us at the same time?

Thanks! I know about the indestructible part. I faced this situation between Doomblade and Colorless the other day but couldn't remember the specific creature it was used on. But thanks finally for a straightforward answer!

So I've googled this question on numerous occasions and it seems I can never find a concrete answer. Will Doomblade affect a colorless creature such as Ulamog, the Ceaseless Hunger?

I was just curious as to what format everyone played in. I've been playing for a little over a year in Multiplayer casual. It's mostly between my fiance and I. We build decks from all different sets throughout the years and play. Most of our decks would be illegal as far as tournament goes but we enjoy this non-restrictive form of gameplay. What does everyone else use?

Alright, thanks! My fiance and I play casually pretty often and we both are still learning some of the finer rules of the game. Thanks again!

If I cast Worst Fears on my turn and target a player and then I die before that players turn comes around, do I still get to control them during their term? I would say yes, because the spell would've resolved before my death but I could be wrong. Thanks!

I don't have a specific card in mind, just a general question. Can you tap a creature (if it has a tap ability) without assigning it to attack someone?