Ulrich, it looks good on you, man. I'd cut the slit in front and back (did it for mine, makes walking and sitting easier too, less like a skirt) whether or not you plan on riding in it.
Here's the thing about mild steel- it requires upkeep. Remember that thing I was telling you about surface rust? Well there's a whole helluva lot more surface area on a hauberk than there is on a breastplate or cuirass- so keeping your maille oiled is actually the best practice to pursue. If you find it to be too much of a hassle, then you'll eventually want to upgrade to a stainless hauberk as those are pretty rust resistant, or so I'm told. I've not had any rust issues with mine, which I'm told is galvanized steel. YMMV.
