Brakes - you need to stop. If you feel comfortable riding brakeless, your legs suffice.
Foot retention - toe clips/straps, or clipless, etc are recommended, but if you've been riding fixed for a long time you may be able to handle platforms. Hell, they're your shins.
Seat Height vs. Bar Height - The seat will probably be higher than the handlebars/stem. A few inches of saddle-to-bar-drop isn't necessarily a bad thing.
Riser bars with a neg. degree stem make less sense than a flat bar on a straight stem, but a lot of people build their bikes from spare parts, in which case using a less-than-optimal set-up isn't something to lose sleep over.