What to do with equipment for other profession

OK I'm a W/mO LVL 15 and at the Kryta Gates right now. What should I do with upgrades/weapons and runes from other professions? If I have unlocked a ele or ranger or other rune not applicable to my profession even if I sell it, it will still be available to any PvP character that I decide to create later on right?

The same with a weapon/upgrade, do I keep it for any further character I may decide to create? If/when I do create another I will find some more of these upgrades/weapons as I have the char progress right?

If I do decide to sell them is the best place in-game,or with a trader?

I know this may seem like a simplistic question, but it is my first time with an online game and while I love the game I find all this trading/crafting and farming a little bewildering/overwhelming.

Only keep stuff of other prof if it is perfect or near perfect. The best place to sell to people is the next town you come to which is lions arch. I would sell most stuff to merchant because there is no use sitting there for an hour trying to sell something to make an extra 100g. later on when you get rare or perfect weapons/items then sell to people.

sell sell sell to vendors untill you ascend.

Thanks I'll do that