How to prepare for a Ph.D. in Clinical Psychology?

I'm asking this for my boyfriend who is not a redditor.

He is currently in undergrad for psychology and is planning on applying for Ph.D.s soon. However, because he's a transfer student, he's lagging behind and will probably finish up coursework next summer. So first question: is it too soon to begin a Ph.D. in the fall?

If not, what are good ways to spend the time off before applying for the following year?

He is probably going to start a research position at a lab in April, so he's hoping to be able to continue working there after he graduates, or find another lab to stay in. Do research labs typically keep students after they graduate? I'm pretty sure it isn't a paid position, if that matters.

The other thing is that he wants to do clinical psychology, specifically. So, while getting research experience is probably great for his CV, what other options should he consider, either as paid work or as an internship, to help with clinical experience?

Lastly: what are the pros & cons of a Ph.D. vs. Psy.D.? He knows that he wants to work in a clinic and does NOT want a career in research or teaching.

Thanks!