Welcome to the forums.
Manual and power steering racks use completely different tie rods. So if you're gonna change to a manual rack, don't buy new tie rods for your power rack.
Changing tie rods is very simple. You undo the bolt, then pop off the tie rod end with a pickle fork - then just unscrew it from the rack. Or, you can get a tie rod end puller (AutoZone "rents" them for free - it does make things easier).
If you do replace the tie rods, you need to get the car aligned afterwards.
Changing the rack isn't hard either, and I've seen rebuilt racks for as little as around $300.
http://www.carsteering.com/addtocart/1986_Porsche/944/Manual_Steering_Rack/80-70163.html or AutoZone:
http://www.autozone.com/autozone/catalog/parts/partsProduct.jsp?displayName=Rack+%26+Pinion&itemId=prod10854&navValue=14600163&parentId=cat10006&productId=60948&fromString=&itemIdentifier=60948_0_0_&filterByKeyWord=&categoryNValue=&isSearchByPartNumber=&categoryDisplayName=Suspension&store=3375&skuDescription=Atsco/Rack&fromWhere=&searchText=&_requestid=214143
If you change out the rack you also have to replace the steering shaft (which runs from the firewall to the rack) - the manual and power shafts are different lengths.
If it was me, I'd keep the present rack - find out what's leaking and fix it, and install new tie rods - overall, it'd be easier and probably cheaper.
If your car is an early 85, then you can replace the inserts in your stuts - a bunch cheaper than replacing the whole strut assembly.
For struts, I used Sachs inserts (under $100 each) in my 83 and they're okay, but if you want the best go for Koni's. But Koni's will usually cost more than double the price.
Our host here, Pelican has great prices and great service for most of the stuff you need (other than the racks - Pelican's prices for racks are kinda high).
Paragon's having a sale on Koni inserts right now - $180 each for the adjustable sport insert - a really great deal.
http://www.*****************.com/Porsche_944_Suspension_Shock_Strut_Sway_Bushing_s/451.htm Koni's really are the best.
LSD - look in your trunk (under the back carpet by the rear hatch latch and you can find the option codes for your car. It'll say if it had a LSD installed.
For jacking points, I usually jack the front under the point where the rear of the control arms attach to the frame - then place jack stands under the cross member.
In back, I use where the front of the control arms attatch to the frame. Never jack the transaxle - they're not meant to carry the weight of the car like that.