Should an e-mail application to a lab for a masters thesis include attachments, or should I wait for these documents to be requested?
I do not know what the customs are in physics, but professors get requests like this a lot, and most of them feel like form letters (i.e., as if a student is sending out a bunch hoping someone will be interested).

If you want to get noticed, be very explicit as to why you are interested in this person and their lab, and if your desired research aligns with projects you know they are doing, say so with explicit references.  Your paragraphs above sound very generic, something you could have sent many places.

Also, please consider:
- if you are excited about a large project the professor is doing and would be happy to do a project for the professor that they need done, say so.  Typically, if you have an idea already, that might be less appealing than being interested in doing something that the professor wants/needs to be done.  Of course, having as specific interesting idea also shows you understand the area and the professors work.
- if you have funding and will not cost the professor anything, say so.  Oftentimes, professors don't have spare funding to pay for a visiting student (especially one they do not know) ever if they wanted to.
- I would somehow (perhaps in the longer document) give an indication of experience you have (don't just tersely list it on the resume).  A big question a professor would have is how much experience you have and how likely you are to be able to do something good in a short few months.

I would also definitely include the attachments of the long statement and resume in your first message.  If the professor gets through your note and is interested, they would probably appreciate knowing more about you before replying.

Remember: the most precious commodity to a professor is their time.  You need to convince them that the time they will invest in you is worth it.