I was a corporate pilot for 15ish years. Made the jump to a legacy airline last year, and I am so happy I did.
First of all, the answer to your questions is “it depends”. I have seen all varieties of scheduling and accommodating vacations and other events. Every department is different. The big issue is that what policy they have in place when you get hired could change in an instant. I have seen 3 person flight departments go to 2 pilots when one quits, and the boss drags their feet hiring the 3rd person. It saves them money, and the 2 remaining pilots are gonna just get the job done, cause that is what pilots do. I could go on, there are 1000 different situations.
Bottom line is, if you want structure and stability with your schedule, do not become a corporate pilot. 5% of corporate jobs are unicorn, perfect jobs that no one ever leaves. 20% are OK, not perfect, but you could probably retire from someday. The rest are dumpster fires that you wouldn’t wish on your worst enemy.