I don't think there's anything wrong with buying them online, there's really good companies out there, so long as you get the prescription done first, as you are, and then re-do it every year- that's where I faltered!
A contact prescription includes the shape of your eye and have to be fit to you. I get the 2 week ones and just don't take them out until then. I use the Accuvue Oasis as they help keep the eyes from drying out. You will need to go to a doctor to get the script anyway, so you can see what they recommend. They usually give you a trial pair when you go to get fitted.
There are brands that are made specifically for continuous wear, the ones I have can be worn for up to 30 days straight. I don't wear them overnight because my eyes get really dry but I find them find to wear for naps etc. I take mine out and give them a clean every night when I take my makeup off because they get covered in makeup otherwise and I can't see my optician told me they're fine to wear in the shower as long as you keep your eyes closed
I'd be too paranoid about losing one to wear monthlys
I didn't even know you could leave contacts in for that long :/ I thought that was unhygienic, plus you shouldn't get them wet in showers etc? I have fallen asleep with Johnsons Acuvue ones in before and it is so uncomfortable when you wake up.