I've taken many of the on demand classes and find that format better the same reason you stated, you can take it at your own pace and have more time to absorb it.
I've passed the foundations and several vcp exams, and the classes alone will not prepare you, you need hands on experience as well as some study guides geared toward the specific exams. I don't think you need to take a class to help you pass Foundations, but you should find some targeted prep material/book etc.
1. It's the same material, same labs, and same standard of instructor as you'd get in a classroom.
2. Extra study and preparation will be required for the exams. VMware suggest that the Install Configure Manage class is closely aligned to the vSphere Foundations exam, and the Optimize & Scale class aligns more to the VCP exam. Review the objectives of each exam by downloading the exam guides - get to those from the VCP-DCV 2019 page. You can attempt both exams before or after you complete any training - but you won't be a VCP til you've met all the requirements.