the current patch made the cata pretty much obsolete, I would rather go with the war horse if you wanted armor.
your build is good, however I would get 100wpf pole, rest 1h which would make you a better fighter once dehorsed.
considering gear: your horse will be quite expensive. breaking even is possible around 50k total gear cost. the following is out of memory so check it out yourself:
22k destrier
3.5k lammelar vest
~2.5k head gear
~0.5k foot gear
~0.5k hand gear
10k heavy lance
9k sword
3k shield
with this set up you will be loosing money on horse, however getting it back when on foot playing non cav friendly maps.
considering side arm: try the elite scimmi, its long, fast, good damage and with 8k a fair deal. maybe even go for normal scimmi, half the price, decent stats.
so: