Agree with the advice to talk to your midwife about how you are feeling.
On the practical issues you've mentioned:
Please don't even hesitate to feed and change your baby in front of visitors. Your baby's needs come first, and everyone knows babies need to eat and poop.
You can say no to visitors, or only while your husband is there to help - you are under no obligation to let people into your house, and you are certainly under no obligation to "host". Visitors know how to work a kettle - they can make a cup of tea, just ask.
You will know if your baby is ill, honestly, because you will know so well what they are like when they are well. If you don't know what to do, you ring your health visitor or go to the GP and get advice. No one knows this stuff when they have their first baby, and it's fine to ask.
Re dropping the baby, if it makes you feel any better, both my boys had their head clonked off the table at least once while I was getting ready to fee them, they are fine.
You may want to stay in a bit, but if you want to get out, it seems like a lot of effort but it's really doable. My husband used to always make sure the changing bag was packed and ready to go before he left for work in the morning, so that I could wrap the baby up, put them in the car seat and leave, without worrying about whether I'd remembered nappies/wipes etc. Once you get used to getting out and about with them, you will do fine.
I had no idea how to look after a baby when my first was born. You figure it out though - feed them, change their nappy and make sure they are an ok temperature, and cuddle them, and that's pretty much all they need for the first few weeks.