Substitoad is an Ignition Effect monster, so can only be used in your own main phases.
No. It is an Ignition Effect, meaning you may only activate Snipe Hunter's effect during your turn.
No, Alector has no effects that can be used in the opponent's turn. His summon effect is something that can only be done in your main phases, and his negation effect is an Ignition Effect so again, can only be done in your turn.
Depends what for. You could tribute it for a spell speed 2 or 3 effect such as Enemy Controller, but not for an Ignition Effect.
yes
yes it would, because when the opponent attacked, it was his turn and the effect carries on until the end of the next turn which would then be your turn. For e.g, if your opponent activated the effect then the effect would end at the end of your end phase. If you activated the effect, then it would end at the end of your opponents end phase.
Yes, you can use activated abilities on your opponents' turn as long as the ability does not specify that it can only be activated during your turn.
Of course not Why would someone chain a card that ends the opponents turn with another one that has the same effect
Unless specifically stated otherwise, by either directly saying so, or the effect is spell speed 2, then a special summon can only be performed in your own turn. Megarock Dragon can only be special summoned by its own effect in your own turn.
Yes, it is a Quick Effect and can be activated in either player's turn.
If you mean for its own effect, then no. It is an Ignition Effect so can only be activated in your own main phases.
The effect he uses to destroy a monster, is an Ignition Effect, so can only be used in your own turns, in your main phases. However his counter-adding effect will add counters in either turn.
Yes. The effect of Ultimate Offering is that by paying 500 life points, you can normal summon 1 extra monster during either your main phase or your opponent's battle phase.