Hi!
Its well worth a visit but you do need a whole day.
I am not sure about opening hours and days.
Here is their website:
http://www.vhu.cz/cs/stranka/vojenske-technicke-muzeum/
During June it was only open during Saturdays and I doubt its open more now.
During July and August I think it was open five or six days a week.
We went by train.
We went to the railwaystation several days ahead and checked (if I rememebr correctly the trains went every hour or so), they understood german ok (better than english at least) and were very helpful.
We had to take a train from the mainstation wich took us to one of the southern stations in Prague were we had to change trains wich eventually (after one and a half hour approx) arrived at the small station at Lesany (its easy to miss).
From the station its a small walk (along the road to the right), then turn left and cross the bridge, follow the river to the right on a path through the woods and you will arrive at the museum.
I really enjoyed the museum, the only problem was that it was very difficult to see the vehicles from different angles and come close to them, they are all behind fences and belive me it doesent work to try and pursuade the staff (and there are LOTS of them!!!), I tried but without any luck.....
There is a rather nice modelshop at the museum but then again Prague has a LOT of great shops, last time I visited Prague (this June) I found some 22 shops.
See my earlier posts on this page for the best ones.
Erik
Sweden