Here is my 2 cents for your Qs (I am arguably the best merc healer or any healee on my server due to my ability to play and where/when to use what casts and cds)
1) I am on my phone so can't link spec but I use cookie cutter build no points in any +endurance or damage reductiin. No points in improved cure as I rarely rarely raaaaarely use it because it doesnt cure sorc dots. Spec into reduced heat on powershot
2) Some people were talking about mobility and this is so true, I can keep myself topped of really well on the fly, spam kolto missile, kolto shell, insta heal if needed. Protip The 40% increased healing while bubbled WORKS with medpack and kolto override. I can burst 15k+ healing on myself while moving in 3gcds and everyone can.
3) If I see 1 person taking tons of damage i pop it and then kolto bomb for 10% damage reduction then spam scans. Orrrr with relic/adrenal on anyone you see with sub15k hp spam powershot then cgc then more ps you will get your 2.5k damage medal np and kb most likely and highly likely to get 1v1 medal(i know medals dont matter too much but I always get 9 or more medals and it helps puggies to vote for u if you are top medals)
4) Use the one with cd on cd for reduced heat on rapid scan and for hot just keep your heat semi in checkcheck
5) I disagree wholeheartidly on this... only time i use rapidshots is if target needs like 500 or so hp to be topped off or if i need 3-6 quik stacks for cgc proc or if i amd running and stacking cgc at the same time.
6) If under no pressure you mean they arent taking much damage spam powershot if you mean noone is focusing you and they are taking serious damage and you need to top them off or sustain heals on them say I am running in and see a friendly at 5% hp i run towards him pop any adrenal/relic i have and instacast no heat proc as soon as he is in rannge hot with the 31 talent point insta heal then insta cast big heal then kolto bomb and he should be topped off. Then i stun the enemy and help kill him while keeping teammate topped. That is best (cd) scenario if i have no cds up i hit him with kolto bomb then (i am terrible with names for skills) the heal with a cd, then spam rapid scan with insta heal when on cd and make sure u get kolto shiled on him when u can.
7) I think this is the situation that separates me from other healers. Dead teammates means you are dead too... i top off all teammates and let myself dip to sub30% or lower without healing myself at all (unless teammates are topped) then i pop bubble medpack (7k heal with bub) kolto bomb 3k crits with bubb insta heL if i have one pop cds and rapid scan crits for 6.5k top myselc off as soon as humanly possible. Then i knockback everyone focusing me then get teammates healed asap and stun anyone back on me.
8) oh there is no 8.... well once again i am on my phone so i apologize for typos and poor skill name linking... i can clean up the post or you can talk to me on skype i have one video on youtube.com/kimjonghealsgaming it may shed a little light... me and 1 other healer on their base's ledge 7v2 while taking throws for caps and gaking serious damage.