I haven't had my baby yet, but I've been a nanny that has worked with breast milk for the past three years and the lansinoh bags are the best that I've worked with. Never had a problem with them busting or leaking... I've had the medela ones leak though. And yes, if you're just pumping and not storing, you can keep them in the bottle with the lid or pour them in the bag, if you're pumping for storage, it's best to pour into a bag and then remove air and lay flat to freeze.
I have a medela pump and just got what was cheapest. The medela ones are double the price. I was just planning on pumping into a bottle then dumping into bags. It's an extra step but saves money.
those are the ones i had on my registry @sarahemccormick . ill stick with those. they were way cheaper than medela. i honestly dont even want the medela pump. but ig its a pump. lol