The quick answers because I am pressed for time & internet connection are :
What can I do for GPP if I do not have access to a sled or a Prowler?
Throw a medicine ball for distance, sprint/walk to it pick it up repeat 10-15minutes+.
Make some sandbags relatively inexpensive then do carries, tosses, medleys, sprints with them.
Walk/Sprint up a hill. Walk around your block 5 times take that time then try to beat it each time you do it
How do I alternate between squats and deadlifts?
Depends on your body (endurance,experience,etc...)
Most simple way is to alternate Max Effort Squats & Dynamic Effort Deadlifts one week then Max Effort Deadlifts & Dynamic Effort Squats so you don't get beat up.
Conjugate method uses different variations of ME for both Squat & Deadlift so quick 3 of each would be Box Squats with SSB, Regular Squats, Rack Suspended GM's and Rack Pulls, Reverse Bands Deadlifts, Deficit/Regular Deadlift
How long should I use the conjugate method to prepare?
Once again depends all on your body. When I get a chance I will brush up on westside to give you better more detailed answers but typically its run in 3weeks cycles. WESTSIDE isn't so much preset peaking or period-ized lifting, but more so a bunch of methods to address weakness' and create new strengths.Louie looks at each individual lifter and pairs them with lifters with similar strengths, weakness, leverages,etc... so that what ever they are prescribed would benefit them.
EHUBBS could prob shine some light and give way better answers then me, but hope this is somewhat helpful