Betta Fish: Info/Question Dump

Hello! I have a few questions that I wanted to ask in regards of my fish tanks but I want to provide some information about what I have and everything first.

Information:

* Currently a 10g Tank with a 50 Watt Heater and a TopFin Silentstream 10 Power Filter with cartridge

* pH is 7.6

* Water Temperature is set at 78-79°F

* Current Tank Inhabitants are 1 Super Delta Betta (My Betta does not bother the shrimp, snail, nor Loach), 1 Mystery Snail (had 2 but 1 passed), 1-3 Ghost Shrimp (I never see more than 2 at a time), and 1 Kuhli Loach (Getting more after setting up my 20g long)

* My Betta does not bother the shrimp, snail, nor Loach

* Plants included are Frog Bit, Java Ferns, Golden Nana, Cuba Ludwigia, Bamboo, Dwarf Sag (I think), Christmas and Java Moss, Golden Pothos

* Fluval Stratum and Black Aqua Natural Sand for the bottom of the tank

* Medium size driftwood, underground cave, betta log, leaf hammock, and other places to hide/rest

Questions:

1. I am upgrading to a 20g long soon (January 2026). At the moment my 10g tank is doing well and I plan on moving everyone over to the 20g long but am concerned/worried that the new tank won’t be cycled. I don’t have the space to have both set up because I’m having to build a sturdy stand to support the weight of the new tank. Would it be okay if I simply transferred the current substrate and water from the old tank to the new along with the filter then added more chlorine free water to top it off?

2. Should I get a stronger filter and heater for the 20g long?

3. Once the 20g is established, I plan on getting more Kuhli Loaches. Would getting 2-4 more be sufficient? What other tank mates (if anything else) could I add to the tank?

4. The 20g long tank has the black trim so I got the Top Fin Hinged Glass Lid but am struggling to figure out what kind of light I should get? The lid is a MUST due to the fact that I have a cat and I wouldn’t trust my betta to NOT jump out.

5. Once my 10g tank is empty, I’d like to put something in that as well at some point but am unsure of what? I really like guppies but would only want to do males due to not wanting to deal with the overbreeding. Preferably something colorful!

I know I’m asking a lot and giving a lot of information but all the research I’ve been doing plus the 50/50 opinions on what I have already read is becoming overwhelming and I’m starting to become lost. I appreciate everyone’s input and help in advance!