I'd try a rotary with scrubbing brush and a strong TFR. You can then finish with red or white pad or maybe even just use a manual microfibre mop.
For the sticky stuff i'd spray (conservatively) a solvent based cleaner directly onto the affected area (I have a UPVC cleaner which works great on sticky stuff. I do occasionally use this with my rotary and it works a treat).
As with all new cleans try a small test area.
I would avoid using your PW & FSC as way too much water, even with a wet vac.
We did a large warehouse (325 sq m) with PW and FSC, no choice as the job demanded it. Even though we sandbagged the only office (studded walls) water still found its way in. We used XL floor squeegee's to push the water out through the loading bay; a real pain. A wetvac wouldn't have kept up, unless you buy one of these from tech-clean (around £1700 if I remember right): -
http://www.tech-clean.co.uk/vacsys.html Your other option is a scrubber dryer, same chem's as above.
Let us know what you decide to do and how you get on.
Best of luck