Posted 02 December 2011 - 05:45 PM
Ok, I'll answer what I can.
1.) You are right Bolting matters little in a TI party. No one is going to notice if you have them or not. Losing them then should be a consideration based on skill requirements and leveling ability. Beyond that they should have no impact on you.
2.) Pre-Renewal, it was about the only thing that could get you in parties. Although I hear fiberlock was used, too. Right now, You can join a TI party as a sorceror and nobody will care if you just stand there and bolt stuff. They'll wonder WHY you're bolting but because every class can AOE kill very fast now, it won't matter what you can or cannot do, as long as the party has the AB (or two) and a killer and/possibly tank. Because of everyones AoE ability, no class is particularly useful in PVM save for AB's and Sorcerers sometime due to their ability to give Sp. It's kind of lame.
3.) Magnetic Earth stops ground based magic attacks. In pvp, it's potentially useful. in WoE, it helps. During MVPing it saves lives. During PVM it does almost nothing at all. Most ground enchants are very, very difficult to use in PVM simply because there isn't much camping done anymore and there aren't too many monsters who just cast and cast and cast at you. It's hard enough using volcano and whirlwind and deluge while leveling on a map. Magnetic Earth is just far more specific than any of those and less useful (barring WoE and pvp and MVP), Depending on what Sorcerer skills you want, you may need Magnetic Earth as a skill requirement, though.
3.1) Extreme Vacuum and Arrullo are WoE/PVP specific. Both skills can not be used on any maps outside of those areas, so they are largely useless if you don't woe or pvp. I'd love to use them myself but simply didn't meet the skill requirements for Extreme Vacuum when it could be used on regular maps and Arrullo has always been barred from operating on regular maps (but I have the skill points to get it in my build-I just can't use it). So as much fun as those skills are, they are useless for us PVM players.
3.2) Bolts are fine at level 10 with high dex. But they're useless if you are becoming a Sorcerer because you will have Psychic Wave, Veretyr Spear, Earth Grave, Diamond Dust and Cloud Kill. If you get the proper level of Call Agni, then you can change Psychic Wave into a fire property magic attack, as well. Bolting via manual cast seems silly. However, if you were a battle sorcerer, then getting the bolts and having Double Bolt are probably pretty good ideas, if not, in most cases, necessary ones.
Hope that helps and thoroughly answers your questions.