Please don't be angry with yourself my love - none of this is your fault and you haven't done anything wrong! I hope I can reassure you as well, so you can feel less scared because actually, there's a lot of really positive stuff in what you've said.
There's a lot in your post, so if it's ok with you, I will take your points one at a time, in the same way that you've numbered them, so you know what I'm answering
1. HPV does NOT have symptoms. CIN also does NOT have symptoms. However, some other, easily treated things (such as bacterial vaginosis) do produce symptoms. HPV and CIN do not though, so your discharge will NOT be because of HPV or CIN. I know you say you have been tested for everything, but I wonder if they've properly informed you of the results. It might be worth asking them if you've been tested for bacterial vaginosis, which is a really common infection which can cause lots of discharge and is easily treatable with antibiotics. Things such as bacterial vaginosis are really common, and it's not unusual for women with mild CIN to also have it, so I'm not surprised that the people you've spoken to with CIN also have discharge. However, this is NOT because of the CIN or the HPV.
2. It's perfectly normal to bleed after a colposcopy and biopsy. Some people bleed a little bit, some people bleed for longer, but this is perfectly normal, so don't worry about that.
3. You might have a little infection caused by the biopsy itself. This is very common. Go to your GP.
4. If your result does come back as CIN1, then it's probably the case that it's been treated by the biopsy already. What I mean by this is that it's possible that what they took out for the biopsy was everything 'abnormal' that was there. If not though, they would most likely ask you back for another colposcopy and remove it then. The whole point of the cervical screening programme is not to leave it in place, but to get rid of it so that it doesn't progress, so don't worry, they won't do that. There is an outside chance they'll do nothing and ask you to come back for a smear test in six months, but probably only if they think they got all of it at the biopsy.
5. If the CIN is 2 or 3 (and it sounds extremely unlikely that it is) then yes, it's possible that you will have to go for an excision and yes, this is likely to cause bleeding. If you're concerned about lots of bleeding then you can discuss this with your consultant before he does the procedure. If they feel it's appropriate, they can prescribe Provera (a progesterone based medication which stems bleeding) but the bleeding doesn't usually last for more than a couple of weeks anyway, can be dealt with in the same way you deal with a period and really is nothing to worry about.
Also, I just want to clarify the difference between HPV and CIN for you. They are two separate things. HPV has NO SYMPTOMS and everyone gets it at some point in their life, and I mean EVERYONE (apart from nuns!)! There is no stigma attached to it and it is not your fault that you contracted it - even barrier contraception doesn't necessarily protect against it so don't blame yourself in any way. In most people, HPV clears without them even knowing they've had it. Even in people who don't clear it, it won't necessarily develop into anything else and they still won't ever know they've got it. However, in some of those people who for reasons that medicine does not yet know, HPV will go on to create CIN or CGIN, which means that you have cell changes in your cervix but this also produces NO symptoms.
It's great that the consulant thinks that 96% of your cervix looks healthy - that is really good news. It's also not the case that you're likely to be facing treatment after treatment. If you've got CIN1, the overwhelmingly likely outcome is that it's been removed by the biopsy and that's that! There is no reason to think it will keep coming back and they will put you on more regular smear tests to look after you and ease your worry anyway.
Several studies have been carried out about folic acid and dysplasia. As far as I know, what they have found is that whilst there might be a correlation between a deficiency in folic acid and the development of dysplasia, supplementing with folic acid once dysplasis has been diagnosed makes no difference to it. There is fairly concrete evidence to show that smokers are more likely to have recurrent CIN though. Keeping generally fit and healthy, eating a good balanced diet containing loads of vegetables, not smoking and not over-doing it on alcohol too often are the best things that you can do, as well as being generally vigilent about your body.
If after all this is over you're still bleeding after sex, then you need to get that sorted with your GP, but try not to worry about that too much as it's most likely to be caused by something really simple, such as your contraception being unsuitable for you.
You're very young to have gone through this and I really feel for you. I know it's easier said than done but, try not to worry - it all sounds really positive, actually - I hope that what I've said helps in some way.
Let us know how you get on.