A titan should always be the jumper IMO. It's the best jump for that raid mechanic plus it's the fastest. Warlock is too slow. Hunter jump IMO is awful for it. IMO it's the easiest part of that raid being the jumper. I don't know why so many people cannot do it. All your doing is jumping from 1 platform to the next and the platforms are HUGE, the guys on the ground have a much harder job to do. I'd much rather be the jumper. I would always do it on my titan, then let others do it when I'm on my hunter/warlock, you need to learn every part of the raid. I hate people who always pick the easiest or same jobs every time;
I'll take left on WOTM
Never using the relic
Never going in the portals
Using self res over stormcaller
The only way your going to be a good raider is if you know every job and put yourself into the tougher positions. The only job I cannot do in any raid is use the sword on crota, but that is because I've never really tried and didn't want to learn and waste everyone's time so let an experienced person run it to make it a quick run. The only part that messed me over when I tried it once was after getting the initial hits on him I panicked getting rid of the sword to blink strike him to go invis. I reckon with practice I would have it nailed but I've never had the opportunity to be able to spend time practicing it. That is essentially what raiding comes down to practice. Once you have done VOG week in week out for 3 months on every character you should be able to do it in under an hour. Kings fall again when it first came out took raiding over 2 different nights (6 hours) to complete within 3 months could do it in 45 minutes start to finish with the right group.
Challenge mode however is a different beast altogether you need a bit of luck on your side as well as a competent group or the right strat for the group, what works for 1 group won't work for all groups. Have 1 person not doing something right and it's a wipe.
You can't expect someone new to be able to learn a full raid in 1 night and you can't just give them the easy jobs to do either as they will never learn the raid that way and expect to be carried every time.