If you buy any mount, either in-game with gold or with crowns, it will unlock for every character that you have. so mounts are decently worth the money. However, all of the different mounts are just skins, and they will all act the same in-game (i.e., when you increase your riding speed or carrying capacity, it will work regardless of which mount you are using). You can also train your riding skill every 20 hours to increase the various horse stats.

If you buy the Imperial pack, then you can craft Imperial-style goods for any of your characters, not just your Imperial characters. You can also change the style of most armors you find to the Imperial style, but this will bind the item to your character.

Enchanting is a good craft to learn, as it will allow you to make various glyphs that will let you increase your health, magika, or stamina on armors, and can give you some cool glyphs to put on jewelry or weapons. As you are new, I would not invest too heavily in more than two crafts starting out. But as you progress in level, you may find yourself with some extra skillpoints that you can put into other crafts.

All NPC stores will buy your items for the exact same price, so you don't need to shop around for the best prices at NPC stores. If you are part of a guild that has a store, you can sometimes sell various items for more than you could to the NPCs, though, so you might want to check that out. Also, if you steal stuff, then you will need to find a Fence in an Outlaw's refugre in order to sell that stuff. Selling stolen goods (especially green or blue items that you can steal) is a great way to make money early on, and can usually pay for all of your other items you might need when adventuring.

As for good money-makers right now, fishing mats (worms, crawlers, bug parts, and guts) are selling for a decent amount. Everyone wants them right now. So if you come across these, save them up until you hit 50 or so, and then try to sell them. you should be able to get a good amount of gold for them.