For example the card Healing Pulse says: Heal 3 every character within 3 squares of you. Do enemies within range count as a character and get healed as well? If so, will it then attempt to trigger blocks in their hand? Any change to the effect in pvp?
Enemies counts as characters yes. Read Melvins rules under help in the menu ingame for more insight into things like this.
Yes, enemies will be healed as well. It will also attempt to trigger blocks in their hand (making for an excellent sneaky use of the card). I don't know definitively that it works the same in pvp, but I can’t imagine that there would be a difference.
Yep. Soaking up blocks is a benefit of healing pulse. It works that way in both MP and SP. So keep in mind if you want to try to get an opponent to use a block for little effect healing pulse, bungled heal and a couple other spells are great for that.
You should see the characters highlighted on who it will be used on also for future cards like this if you test in battle.