You can store your MWF in the container it comes in. It'll be fine, even without daily watering.
I learned on the EJ89, it's a good razor, and not just for learning, it'll serve you well. My recommendation is to get one blade, like the Astra, and stick with it until your technique is nailed. I think you'll learn faster. If you have a really tough beard, you may want to go with something a bit sharper - Gillette Yellows, Personna Med Preps, or Feathers.
As for your very last question-- that's a toughie. I recently had to use a cartridge razor for a couple of days so I have current experience to compare the two.
- It all depends on what you mean by a "better" shave. If you're like me, at first you will definitely see a drop in overall quality. I didn't get as close a shave, and I had frequent bouts of razor burn. But I had enough good days that I stuck with it.
- I think the overall closeness of the two is similar, maybe a tad closer with DE.
- I found the cartridge was harder on my face. It "scraped it up" more, it was almost impossible to avoid razor burn, and I was applying all the techniques I've picked up DE shaving, so it was about as good as it gets.
- The DE razor is definitely easier on your skin, once you master it.
- The DE razor is a lot more fun. It's a skill that takes attention. Plus, the single blade sliding over your skin, and the sound of whiskers being cut just can't be approached by the cartridge.
- Bottom line, using the cartridge after 6 months of being away from it did not make me want to go back. The only advantage to the cart is that it takes less time.
If you decide to go DE, here are my thoughts:
- Read the ShaveWiki and the links at the top of this Shave Clinic.
- Watch Mantic59's videos on YouTube. If a picture is worth a thousand words, a video is worth... 10 thousand?
- Use a good prep. This can be as simple as leaving your face wet from a shower, lathering up, and letting the lather soak your beard for a couple of minutes while you get everything else ready.
- Use a good post-shave skin routine. Here's the one I use, FWIW.
- I rinse the lather off and apply a generous portion of Taylors Witch Hazel over my entire face, neck, ears, etc. (It would look a bit funky to have nice-looking skin only on your cheeks). WH is really good for the skin.
- If I have razor burn, I apply an alcohol-based aftershave about 10 minutes after the WH. Yes, it stings, but it also kills the razor burn fairly quickly. I use Old Spice, or Bay Rum, at the moment.
- In the winter, I rinse my face again, and leave it wet. I apply a fair amount of Nivea Sensitive After Shave Lotion (actually a balm) to my wet hands then rub it all over everything, again. I find Nivea works best if I use a fair amount and cut it with water to make it spread easier. Otherwise it feel sticky later on.
Note: Using this routine, I've gotten compliments on how nice my skin is from women who don't know me. They were all from women because guys don't notice other guys skin, and if we do, we don't talk about it! One compliment came from a skin care consultant at Neiman Marcus. She ended with, "Whatever you're doing, it's working. Don't change it!"
Good luck to you.