LOL! These aren't dumb questions, it's good you want to be clued up.
I think basic tests you want to have done are the routine first set of bloods (varies from PCT as to when they do them) This will do a full blood count, your blood type, immunity to things like ruebella as well as checking for some diseases like HIV. The new downs test is carried out between 10& 12w+3d, but this used to be done at 16 weeks, called the triple test where they checked for downs, spina bifida and one of the other trisomy numbers I think. There is also a blood test at 28 weeks to check iron levels for anemia. That should be it for blood. In most area's 2 scans are available, a dating scan between 10 & 14 weeks and an anomally scan between 18 & 22 weeks. I am not sure how it works in other areas, but where I am we are not offered an NT scan unless they pick up markers at the dating scan. Checks that are carried out as routine at every visit include urine, blood pressure and after 12 weeks, fundal height (measuring your belly from top of pubic bone to the top of the uterus with a tape measure!) and listening to baby with a doppler or one of those weird ear trumpet things, can't remember what it's called now.
I think that is it, but it has been nearly 4 years since I last had a baby. Hopefully if I missed anything out, someone will point it out. Oh, I had to have a glucose tollerance test with my first pregnancy but not with my second. Not sure if that is routine or because I measured large with ds1?
These were the minimum tests I was offered the last 2 times. It never occured to me that I could refuse any tests, I just went along with them because I was told to have them, lol! Just remember, it is your choice and you can have them all, or as few tests as you want. I even know someone who refused her scans as well.