Yes, I would "exercise" the lifting system now and then. Hydraulic seals tend to deteriorate if they don't get movement, and a little hydraulic fluid, past them.
The top is being supported by the cables when it's up. But, they are easily able to handle that load. I don't really see the need to support it with 2x4s, but others will probably disagree with me on this. Extra support will not hurt, but the boards need to be long enough to keep the top half up to the level where the bulb seal meets the lip on the lower half, to keep out bugs and cold air.
If the cables are not fraying, or rusting, they should last indefinitely.
Hi-Lo 1707T - Tire Minder TPMS on Tow Vehicle and Trailer, 300W Solar Battery Charger, Equal-i-zer WDH, Progressive Dynamics Converter, Fan-Tastic Fan
2014 F150 Platinum 4x4 3.5L EcoBoost SCrew