Buildapc

I have an AM4 based desktop with the following current configuration:

• Ryzen 2200G CPU
• 8 x 2 DDR4 3000 MHz RAM
• RX 7600 GPU
• Gigabyte B450M D3SH motherboard
• Corsair RM550 PSU
• 1 GB M2 NVME disk
• 2 HDDs - 1 mirroring the NVME and the other as data drive
• Acer FullHD flat panel with FreeSync

Goals are casual gaming at 1080p or slightly lower resolution, target fps 30+

Please give me suggestions for:

1. Best AM4 CPU available now (a) with no integrated graphics (b) with integrated graphics.
2. How would you rate Ryzen 5700G for this setup? It is available and budget friendly.
3. Can I buy 3200 MHz RAM to fill the 2 vacant RAM slots in my motherboard so that I can continue to get dual channel benefit? 3000 MHz RAM seems to be no longer available from the brand/locally.
4. 1 GB SATA SSD for cheap purely to store game installations (Crucial BX) but there is no spare SATA port in the motherboard, is there a way to connect 2 HDDs to same SATA port?

EDIT 1: I think there are 3 HDDs and 1 DVD drive occupying all 4 motherboard SATA ports. I erred in the post above earlier.