About your Brussels-Tours trip, I played around with the German rail
site and found that there is a direct TGV
train from Brussels to St-Pierre-des-Corps just outside Tours. You
can consider that your arrival point in Tours or take a 5-minute
local train to the central Tours station. This would save you from
changing stations in Paris. It leaves Brussels Midi Station at 7.04
a.m.; check if it runs the day you want to go.