See the C41 howto in my FAQ, link in my signature.

Always prewash. Don't use blix if you can at all avoid it. If you must have blix, make sure it's a kit where the bleach and fix parts are not mixed together until you use them, use them up fully and discard them within a day or so.

For 4x5, I use a 3010+CPP2. You will NEED a water bath. Doesn't need to have a powered roller, you can hand-roll a tank on a pair of submerged bearings but your arms will tire as C41 calls for CONSTANT agitation.