First re inflation... inflate each tube section in turn until it's full but no pressure (still a little crinkly) then go round and take each to full pressure... actually I'm a bit OCD and do this in three gradual steps. This will preserve the life of the internal baffles.
Yes the valves are supposed to leak by a little with the caps being the final seal.
Re wheels... is it the strong buoyancy making them awkward? If so half fill each inner tube with water... that will make it easier. Another option is to buy smaller wheel/tyres from somewhere like Machine Mart. They will still roll well on the slipway but have far less buoyancy (you do need to make sure the axle bore is correct).
My flip up Trem wheels just need one pin removing to take the leg off when you pack the boat away and this leaves a small bracket each side on the transom. I put a bit of foam over this as I fold the cone ends in to protect the tubes. Have a look at post #23 in this thread for some images of mine...
Trem HD flip up wheels on an Aerotec
The only small thing against them compared to the OE wheels is their lack of length so you have to tilt the outboard right up.
Re that Rooteq trolley looks good if a bit pricey. I use this type which is good enough for a 15hp but a bit flimsy in truth...
Re speed... a 15hp will usually take an Aerotec to 18-19Kts. Others with a 25hp might comment but I'd have hoped for nearer 25Kts with your outboard... however I wonder what pitch prop you have? Should have that stamped on it or a part no. you could Google to find out.
Finally... we have been talking about Aerotec transom splash in another thread... do you get this at all at speed?