Phyrexian Unlife Some might see Phyrexian Unlife as a card that simply gains you 10 life, that does nothing against infect
Youthful Knight is a 2/1 with first strike, so if it was blocked by Alpine Watchdog, Youthful Knight would deal its two damage first, destroying the Alpine Watchdog before the Youthful Knight would take damage
Theres a lot of established heuristics on this subject, and a few points I can toss in to help you construct an optimal mana base for Standard, Modern, Pioneer, or whatever MTG format you prefer
Commander is an incredibly popular format, easily claiming its current place as MTGs most popular in-person game type
No, burn decks can be viable in various formats in MTG, from Standard to Modern to Legacy
Kellogg, Dangerous Mind wont warp the format or anything