I would avoid downhill - being you have never done it before. too high a risk of injury leading into a decient meet. You might not and you might. a 50/50 chance of getting injured is way too high a risk.
I would not run the Tue race, unless you could run 95%… but i think not.
Do the 10day taper as outlined - really recover and run well.
If you feel your top speed is lacking (which i think its fine) you could do some fly 20’s.
I think your area of focus is the Transition from blocks to full speed. Around the 20-30m mark.
Keep your prize in sights big fella (the race in 10days). The little races you can forget