New(bie) Herioc: worth going back to do earlier progressions?

As far as your old account and char's go. If you have the email address (working or not), and the original/last credit card used on the account, customer service should help you recover the account. Just be very patient in contacting them since they seem to work verrrryyyyy slowly!

Once you recover the account (you WILL have to subscribe for at least one month, but you could purchase a Krono in game and give it to a char on the account to subscribe. Cost will be dependent on the Kr cost on Vox, I can't quote it here since I play on Phinigel where the Kr cost is so much lower (around 3-4K per Kr). Once subscribed, you purchase a character transfer token for each character you want to move to your new account. Remember that the max number of characters allowed is limited. You start at 8 and can purchase 3 more via the Marketplace. There are a couple of other ways to get slots, but some may not be possible at this time.

As far as epics, your 1.0 is totally solo-able with an HC (I did it with my cleric in about 2 hours). I THINK that the 1.5 can be soloed, but the 2.0 takes at least one raid to get some of the items needed (for all classes). I am sure that there would be several 105 characters willing to help you, especially if you get into a guild.

Good luck and welcome to/back to the game. You are in our world now!