I have a 800mAh 2s lipo and it takes a long time to put it on storage from 100% charge. How long should it take? What exatly doesthe storage mode do? `Does it put bthe battery on 50% charge? Does it lower the Volts to half or the Ampers?

This is the charger im using:https://www.amazon.co.uk/SKYRC-E6650.../dp/B00PFVH2PA

Yes, it's normal. Those basic chargers don't have the high discharge capabilities of some of the high end units. Even at the maximum 1amp discharge rate of your charger, that you linked, it will take a long time to discharge a full pack down to 3.8v/cell. I've never seen any of my chargers use their maximum rated discharging spec. If I don't plan on using a LiPo pack within a day, I use an automotive turn signal bulb discharger,
and LiPo battery low voltage alarm to quickly drain the pack close to storage voltage (3.8v/cell), then I throw the pack on a charger to finish up.

The LiPo Storage function will either use it's own discharge rate or it will use the rate set in the LiPo Discharge function. Depends on the charger.
In the Storage screen hit the Enter button and see if the current will flash and if it does then use the up/down buttons to change it.
If you can't change it there then go to the LiPo Discharge screen and change it there.

LiPo Storage is mandatory if you want your packs to survive a long time. Storage will either discharge or charge the pack to 50% power. Once at 50% you can stor the pack for monthe or years without fear of cell damage.
Never put a pack away full charged. The cells will become damaged by high resistance and not deliver full power.

If you have a fully charged pack and won't be using it for longer than a week then put it in storage.

After a run should i put the lipos in storage mode if i will not be using them in a while or balance charge them first and the put them on storage mode?

You can just charge them to a storage voltage. Around 3.85V per cell. Doesn't need to be exact.

Sounds not normal. Nominal Capacity is 4.15-4.2 V per cell.