No, both cards target, and Obelisk cannot be targeted. Use Widespread Ruin instead, it does not target.
Blue-Eyes Shining Dragon can negate effects that target it. Magic Cylinder is a targeting card, so yes, Blue-Eyes Shining Dragon can negate it.
No, Magic Cylinder is not currently banned in the official TCG banlist. It is a legal card to use in most tournaments and games.
A cylinder was used as a target before the board.
Yes. As long as you qualify as a legal target for the spell, you can choose yourself as the target.
A permanent with shroud cannot be the target of spells or abilities.
America - you can do magic
No, note the difference between 'negate' and 'destroy'. When 'Magic Cylinder' activates, it doesn't matter what happens to the 'Magic Cylinder' card, it will not stop the activated effect from resolving. Chaining 'Dust Tornado' to it will do nothing. What you need is a card that will negate the effect too, such as 'Trap Jammer' or 'Solemn Judgment'.
it meens what chance there is that it will hit it's target
Target should sell Magic cards, there may also be independent sellers in Tamworth.
Yes. If Magic Cylinder or Dimension Wall's targets leave the field before they can resolve, they will not deal any damage.
Rank-Up-Magic Limited Barian's Force's only real advantage is that the monster it summons can be a different Type than the target. Rank-Up-Magic Barian's Force can only summon a monster of the same Type as the target.