Welcome to the Longhorn world. They are a little different than other breeds when it comes to handling facilities. You will need some variation of a "Medina Hinge" setup to work the bigger cows. See this thread for explanation of a medina hinge
http://cattletoday.com/forum/viewtopic.php?t=4336
As far calves, you might be able to work them in the same set-up, but I would prefer a Priefert brand headgate attached to the end of a 28"-30" wide chute. I would use the headgate to work small to medium sized calves that don't have much horn yet.
How often you might need vet care really can't be determined. That is like saying how often do I need to go to the doctor? The answer would be "Anythime you are sick and can't diagnois and treat yourself". The same answer would apply to your cattle. No matter what, you will still need some type of loading system (i.e. pens) to get your cattle into a trailer. As far as annual vet care, I would say they need to be wormed 2
times a year, and given an annual blackleg and triangle-9 vaccination, at the minimum. Who knows what else migth come up?
I am currently working on a set of pens to work longhorns. To give you an estimate, this is close to what will be spent (materials only), although it is not finished yet.
64' x 64' pen (perimeter with one 12' gate)..................... $1,400
Internal alley, Medina Hinge set-up, and loading chute......$1,100
Headgate (Priefert manual)............................................$ 400
Trailer 14' stock trailer (used but great condition).............$1,500