Portable bluetooth speaker design

I want to get into DIY electronics and the bluetooth speaker in this instructable seemed like a cool project. Unfortunately most of the components used in the original project are now unavailable and there is a lot of assumed knowledge when it comes to wiring the components.

Based on the project photos (see here) and my own research, I've come up with the following alternate components and a diagram of how I think they should be connected. I'd appreciate any help regarding component compatibility and particularly with my "wiring diagram". It would be great if you could point out if I've got anything wrong, why, and how I can fix it. I'd really like to improve my understanding of electronics. Suggestions for further reading would be appreciated.

Components

• 3.7V 900mAh Li-ion battery
• Lithium battery charging module
• 2-channel 3W PAM8403 audio amplifier board
• Stereo audio bluetooth speaker module. Pin definition can be found here. Side note: The bluetooth module pictured in the instructables project looks like this one, but I can't figure out how to get audio out of it. Unfortunately the bluetooth module I've chosen is tiny and will be very difficult to solder (Especially for me, I've never touched a soldering iron before. This project is going to be a hell of a learning curve). Alternate bluetooth module recommendations are very welcome.
• SPST switch similar to this

Additional Notes

• The original project also has and auxiliary audio input (it looks like it's somehow connected to the bluetooth module in this picture. I don't require an aux input, bluetooth only is fine.
• For the bluetooth module, would it be possible to "hack" a bluetooth receiver for a car like this one. For example:

1. 1. Remove plastic casing
   2. Connect USB cable to receiver
   3. Cut USB cable, then cut the 2 data wires
   4. Solder the positive and ground wires to the circuit
   5. Somehow solder the left and right audio out wires to the aux barrel jack on the receiver?

Thank you for your help.