if you have a soldering iron it helps but can be done with heating a coin over a stove a placing on filter to heat up and aid in removal if you do not remove the filter it will limit the distance vastly and block most of the ir torch capacity to illuminate
i would opt for a 98 or if i was you and to be honest the tune will make the rifle no more accurate than it already is , the difference with tuning is it will smooth out the action and recoil making it simpler to achieve accuracy.
16mm lens would be better and you would need to remove the ir filter from the camera before fitting the lens, this coupled with a t20 ir torch should be good for 100 to 150 yrds
Nice one mate and have a look on ebay for a t20 or t67 ir torch looks like you have a small cree style ir torch from the pic the t20 should be fine for air rifle ranges dependant on camera
my opinion on hawke sidewinders are generally good for hunting not the best for low light shooting and good when you can adjust parralax to suit range. But for target disciplines not the best for hft as suffer badly with parralax error when not dialled in even with consistent head positioning you get problems and the bigger the ojective lens the the greater the parralax error. again all comes down to personal preference and what suits one will not suit another i love the hawke rets the half mildot and sr pro are some of the nicest. but if i was to buy a hawke scope it would be a panorama hal