Sorry you had to find us here. It sounds like you caught your melanoma very early. Do you know the depth of your lesion?
As for just having surgery, that's really all there is for an early melanoma. There are no blood tests for melanoma. Certainly, you could have your GP do baseline tests, but they usually do that as part of an annual physical anyway. Blood tests just really aren't that helpful.
As for having other moles with melanoma, it just isn't that common. Only about 8% of the melanoma population EVER have another melanoma primary. It can happen, but it isn't all that likely. The key thing to watch for is something that is very different from everything else, or something that is changing. Those are things that are more suspicious for melanoma but they don't have to be melanoma.
I was diagnosed 18 years ago with an early melanoma. I just had the WLE (wide local excision) like you. Since then, I've had 2 other melanomas – both with just the WLE. The last one was 9 years ago. I'm still here, still early stage, living life but being watchful.
Life goes on and things get easier with time. The key is to be vigilant, but not paranoid. Practice sun safety and get on with life!