wow, that's a ton of questions/problems, i'll see if i can answer them all.
teachers are hard to come by [though i did notice xEmbraceX said she'd help you with deviation] if i were you i'd look into joining a coven that teaches things you wish to learn. [my coven might be able to help you, we do teach basic divination, this month it's about herbs though] the right coven should provide feedback, you should feel safe [like a family] and feel free to ask any question.
tarot cards, like all divination, can show you a glimps of a potential future. the trick is being able to achieve it once you know the answer. i was taught you should forget you even had a reading, unless there's a warning, or a future you didn't like. otherwise, you'll walk around acting differently, this can effect the future enough to change it. some say just having the reading could be enough to change it. it all depends on how far we're talking in my opinion but there you go.
sounds odd to me how bullying can effect your ability to grow as a person, but i can relate to being bullied bad enough to effect me to this day. i'd meditate, try to come to terms with what happened, and leave it in the past where it belongs. i've done this, it's painful to relive things, but you'll be stronger because of it. or, just tell yourself they're jerks and you'll become more successful than them.
magically speaking there's not much that can be done. there are illusion spells that can help decrease the visibility, but the scars will remain. try shea butter, it's said to diminish [sometimes remove completely] scars, burns, and stretchmarks.
if you're over 18, there's nothing lawfully they can do. if you're under, they're your parents and you have to obey them because they're responsible. once you're legally an adult though who cares. try to explain to them Wicca is not evil, there's no devil, it's about nature and living a balanced life. the old defense of "Thou shalt not suffer a witch to live." is actually mistranslated, the correct translation is 'it is wrong to let an evil sorcerer live' but the bibles been changed so many times, things have been added and removed for political reasons over the years, that it doesn't much matter. plus most people who will argue with bible passages are usually close-minded and not worth the time/energy. just be the best Wiccan/person you can be, don't throw some huge hissy fit and threaten to curse them, and they should come around, once they see you're happy, and not doing anything 'evil'.
try vitamin D, depression runs in my family [along with seasonal affective disorder] having vitamin D normally lessons the depression, and some of my family don't get depressed at all after taking it. when you feel down, try calling the Kids Help Phone [if you have one in your country] it's toll free and anonymous. the other option is to have some sort of outlet, like writing, art, hockey, gardening, video games, even Wicca could be used as a mood elevator.
a tarot reading might help you figure out what you wish to do, but you should try other things, like meditation. sometimes the answers can come to you while your mind is blank. if you keep zigzagging your path, research as many paths as you can until you find one you feel whole in.
a witches bottle or honey jar spell could bring success, attracting good. to repell negativity, i'd do a cleansing with sage, and then a protection spell to keep it away. daily shielding will keep a lot of negative energy away, and some big monthly protection spell or charm can do the rest. as for a spell to hide in the shadows, again,k an illusion spell could help you go unnoticed, but you won't become invisible. no, you can't make the sun go away, try carrying an umbrella to keep the sun off you. the sun is important though, that's where you get vitamin D. if you burn easily, try a sunscreen with a high SPF.
i think that's all your questions. good luck to you, just keep your chin up, and focus. if you want to become a hockey player, practice all you can, on and off the ice. just remember very few make it to the majors, so have something to fall back on just in case.