being nervous isn’t going to help. It sounds like you have provided everything they asked for. Anything anyone offers for a reason is just a guess….
That being said they have had a huge issue with scammers running through there so I would expect Nigeria to get extra scrutiny. If you don’t know why, congrats now do a search for 419 scam. 555
just list the first place you will stay. Or since you aren't limited in when you actually need to enter the country during the validity of the visa just put the address of any hotel.
It doesn't actually ask for proof and is leftover from a previous visa application. Like when they ask about the flight info. Not really needed for the DVT but if you aren't smart enough to find something to put in, you probably aren't worth letting in anyway.
It isn't hard just double check your information before final submission.
Take your time you don't need to do it all at once.
They will ask for clarification or additional information if needed. The people who lose their money are mostly putting the wrong name or passport info etc.