If you just finish the games you'll gain titles without much effort, not to mention the rewards (skill points, gold, etc) that go along with it. You'll have to finish EOTN anyway just for the tapestries to hang in you Hall and probably PvE skills.
I wouldn't use anything from before. For example, Skeletons have been added to UW to mess with 55's and other enchant-based builds. Check PvXwiki for current farming builds. The PvE-only skills are widely used in the farming builds, so that also requires some rank to make them effective. Note that there has been some tampering with PvXwiki so if something seems whacked, it probably is. You can check the more current farming builds in the appropriate boards here on guru.
HoM is account-based. The rewards will link to your GW1 account and apply to a GW2 account. So just like the /bonus items available now, you can create the HoM-reward items for each toon. The exact mechanics haven't been released yet.
|