do i have to do the bird skip, and pillarless? can i use my own route?

I'm sure you can us your own route that is how speedrunning works

If you're talking about doing LBLJ, part of the thing thats gonna save you time in the route is doing those specific stars since they are faster. If you're not confident in stuff like that to start, just do the No LBLJ route. https://ukikipedia.net/wiki/RTA_Guide/16_Star

those skips are just the fastest for top times but you can complete an speedrun the way you want with the stars and strats you want; scroll to a run in the 40 minutes mark and im quite confident you will find people not doing hard skips

check the general and category rules for all you need to know about

You can always use your own routes, some are just faster than others. But for you route X might be faster than route Y for everyone else.