The order to load the MSP is "resupply". You need a maintenance facility and MSPs on the ground, or a supply ship with the appropriate MSP transfer component (can't remember the name).
Maintenance life describes the average time the ship can continue repairing components before it runs out of MSP.
Note that components break down faster the longer a ship has been deployed (so, on average, your ship will consume less MSP for repairs during its first year of deployment, and more during its fifth year). This is followed by the TSO (Time since Overhaul) value.
Maintenance facilities allow 3 things:
- MSP Transfer
- The TSO stops ticking up when in range of maintenance facilities with sufficient capacity
- You can reset the TSO to 0 by ordering an overhaul at a place with maintenance facilities
I am unsure whether components continue breaking down if you are in range of a maintenance facility, but as the ship would be resupplied nearly instantly this shouldn't be an issue.
The "Intended Deployment Time" is linked to crew morale. It changes the amounts of crew quarters on the ship. This clock is reset, independantly from the ship's maintenance, by resting the ship at a place with a population of at least 50K, or with a recreatioanl module.
As a more general comment, you might want to reduce the maintenance and intended deployment time and get a more powerful engine, both from an efficiency point of view (I don't have the calculations here, but you might even improve your range), and from an RP point of view, though this entirely depends on your vision and story (20 years of deployment is quite long to stay confined with 50 people. . . ).