If a land has an ability that says it enters the battlefield tapped, you choose the order in which that ability's effect and Spelunking's effect apply
Life Tap Myrkul, Lord of Bones is an expensive investment so you want it to stick around once it hits the field
Thanks to Tegwyll itself, even if you have a strong board presence, you can use Tegwylls Scouring to reset the board at Instant speed, draw a bunch of cards with Tegwyll, and untap with a handful of fresh cards and three Faerie tokens
1 Deliver Unto Evil
Obviously in a competitive tournament, where there are prizes, proxies will almost always be banned, but in casual formats, like Commander, "proxies" are common, and I, personally, don't see any problems for the most part, although I don't use them
(If you're playing Planechase, proceed to the next plane.) Playtest cards aren't legal for play in any tournament format other than Mystery Booster Limited formats