Mast foot: John Baker's original instructions as reproduced in the Seal 22 Technical Manual say the bolt should be in the "third hole back". Presumably this means back from the front of the T-bar. The picture shows one hole clear exposed in front of the mast foot. On my Sinbad, which may not be the same, I had the kicker in the back hole and the mast foot bolt in the next one forward. You need one hole forward of the foot for the pole downhaul.
Rudder: Have a look at the pic in the thread "Drying out.........Hic!" 7 down from here in this forum. It shows the run of the downhaul through the lower pintle bracket on the transom. It is disconnected and dangling in the pic but it attaches to the hole in the front corner of the rudder blade. When the rudder is pulled hard down the corner is against the green plastic stop and the leading edge is vertical and in line with the pintle axis. It should not be possible to pull it forward of vertical unless you have lost the stop! Or maybe you have the blade fitted backwards! It has been known!
Forestay sag and weather helm: Off the wind all the sail and therefore all the drive is to leeward of the centre line so there is bound to be a net turning force trying to make the boat round up. This is weather helm and is a good thing! An unbalanced rudder will make it seem like hard work. On the wind with the sails pulled close in there will be less weather helm until the boat heels enough to put the rig to leeward. That's why she'll try to round up in the gusts, again a good thing! The 22 rig without a backstay relies on the backward force of the sheeted-in main on the mast to increase the forestay tension on a beat. The harder the main is sheeted in the flatter you can get the jib. If you have a reef in the main the leech tension in the main is pulling closer to the top of the forestay and has even more effect.
More tips in "Sinbad Rudder Downhaul" 4 down.
Geoff Harwood