I would start here.
Remember order of buying new things.
Buy basics at first and then expand.
What are you not sure about?There is not a lot of difference on the inside between watches of this price range. They are either a quartz or a low cost mechanical movement. In that case if you like the looks of the DW, I would get it.
For your first question, I think that your thought is fine.
In regards to question 1, I am not a bowtie kind of guy but the one you have selected looks a bit ugly to me. Like making your groomsmen weare aqua vests or something. I would select something more classic like a pindot or a patterened bow tie of a more reserved colour.
I thought it might be Fluco or CWS. I have been a bit suspicious of Fluco since they are priced pretty low for cordovan. CWS is almost double the price but they look really nice. I thought it might be them.http://www.coolwatchstraps.com/Cool_Watch_Straps.htm
I always liked the EZM3 or black bezel watches better from their diver selection but I haven't seen them in person. A bit like blackmail they way WB increased Sinn prices and kept sending out reminders of the impending deadline. Speaking of Sinn, does anyone else love the 103 Klassik?