150 is pretty typical for open houses around here. That's about what we had at my daughter's last year. Because his is the day before graduation (we planned for some out of town family so they could attend both the open house and the graduation in a short period) there's not a lot of other open houses going on. I'd say about 75 people will be there the whole time and the other 75 for a shorter period spread throughout the day.
Thanks for your comments everyone. I'm going to take that and some comments from my meat world friends and do some menu adjusting. I appreciate the feedback!
For the shredded cheese, estimate a 1/4 ounce of cheese per planned taco serving, then add about 10% for spillage.
For meat, estimate 2 oz per taco. In my area it would be around a 60% beef to 40% chicken ratio.
For jalapenos we'd have at least a gallon jar and a couple of 24 oz jars for backup.
For Queso, I'd estimate 30z per person... some will eat more, some less. I'd also estimate about the same for chips.