Stocking Questions About My 64 Litre Interpet Aquarium

Hi guys,
I'm looking to pick your knowledgeable brains again! I have a few questions (that may be a bit silly sorry!)
64 litre interpet aquarium, 64 cm long, soft water area.

I've had my tank for 18 months, but have had to move it twice in that time due to a drawn out house move. When I moved to the new house I bought a slighter bigger tank. With your previous advice I set the new tank up with live plants and left it for a few weeks, then transferred the fish across with the old filter media. The fish have been in for 4-5 weeks now and water quality seems good and steady. Due to the move I haven't restocked so am very light (2 slender rasbora and 1 false julli Cory, all of which I have had since the beginning). The Cory is doing well, but the 2 rasbora not so much..... I just don't think they have dealt with the moving very well.

Going into the future, I think I would eventually like to try having 2 electric blue rams, although they will be the last thing I stock wanting to establish the tank as much as possible first.
I feel now is the time to start restocking my tank slowly.

Questions !!:

1. I'd like to get some friends for the Cory. Can I have different types of Cory, or is it best to have the same type? I wasn't sure on their social behaviour when it comes to mixing types, e.g. False julli, panda, albino etc.

2. I would like to have some tetra as a shoaling fish rather than the rasbora. My problem is I feel a bit sorry for the 2 I have there at the moment. They are fluctuating in colour, are skinny and hide all the time. They never used to be like this. My water quality and temperature are all ok. I have been keeping the lights off and they are in a very quiet room. I'm not sure if adding more rasbora to form a shoal would help? But then I will be in a rasbora cycle rather than being able to have some tetra.  !Or are they just older and been through a rough time? Would adding a shoal of another type of fish help? Any opinions or advice on this would be appreciated.
If tetra is a possibility, which type would you recommend to be with rams in the future?

Thanks for any advice!

Not much to add here though if you are feeling limited for space but want a schoaling species perhaps look at 2cm fish such as the chilli raabora, celestial pearl danio, or ember tetra for example.

I would agree that adding more harlequins might help, I suppose the real question is whether you want to keep these fish long term?

When I got my espe's rasboras I did not have any floating plants and the fish just huddled together in the back corner. After reading that they appreciate cover, I got some water sprite. As the plants covered more of the surface, they ventured further and further from the corner but only to the edge of the plants.

I would not recommend water sprite for a 64 litre tank as it grows quite big but there are smaller floating plants, starting as small as duckweed. I find that hornwort also works well as a floating plants and I've read that Brazilian pennywort can be used that way as well.

Thank you!
I went out to get some floating plants but apart from salvinia I couldn't find any of the recommended plants (I'll have to buy online). Instead I got a large plastic plant and a floating Lilly thing I found in pets at home just to see if it helped. Is made a massive difference already! I can actually see fish in my tank now  and they ate pellets for the first time (that I've seen) in a few weeks, plus their colour is much better over the last 48 hours.
Will definitely try some pennywort!
i went to about 5 fish shops and no one have false julii cories so will have to wait to stock!

Out of interest Matt, what have you got stocked in your tank?