The toughest part is routing the hose. And, the advice about the exact length is right on target. Even if there is excess length don't be tempted to go with a shorter hose. The hose lengths are carefully calculated in order to balance the pressures reaching the cylinders. I know for a fact this is true for slide-out hoses and is likely true for jacks.
Unless parts availability is a problem, you can also order exact replacement hoses from HWH. Each hose has a collar with a part number on it, usually starting with AP.
If the hose is routed through some tight spots, you can simplify the process of installing the new hose by getting an appropriately sized brass connector to connect the new and old hoses together and use the old hose to pull the new hose through.
The bleeding process is pretty straightforward, tighten everything, pressurize and carefully and slightly loosen the outboard end of the hose to let out the air bubbles, being careful to catch any fluid with a rag.
Here's a link to HWH's hydraulic and electrical diagrams that will include the part numbers for the hoses:
https://www.hwhcorp.com/winnebago2017_diagrams.html
And the best way to deal with hydraulic fluid stains is to spread out plastic under your rig with cardboard and kitty litter under the prime leak points. don't ask how I know this.
You'll also have to top off your fluid after bleeding. If you overfill it won't damage anything but just cause a mess since the tank will automatically bleed off any excess. Here's a link:
http://www.hwhcorp.com/mi16_02_oillev.html
You'll also find a wealth of information here:
Tech Support, Manuals, Online Schools – General Information – HWH® Corporation