Combination OK?

[Ajax Bay]

OK. In this case I'm pretty sure a 6sp block will screw onto the hub and the locknut that side will still be proud of the smallest sprocket.
If it's not then you could, if inclined, shift the cones right and redish the wheel. You don't 'need' that 6sp block (I've shared above the work-around to use the items in the OP together).

 

[potosr]

Thanks very much for your answers, they are very helpful for me.
Now, I want to verify if I understand well :
- if I want to completely change my rear drivetrain the steps I must follow are :
1. Buying new rear wheel. Here, I think the most important informations I need are :
- the OLD of the hub (which must be level or narrower to my frame spacing)
- what hub is (for casette or frewheel)
- what axl (to fit with my frame)
2. Buying (using) a freewheel or casette for X speeds according to the hub
3. Buying (using) a RD according to the freewheel or casette and according to my frame (direct or on axl)
4. Buying a shifter according to RD
If I need another informations, please tell me.
I hope the post isn't off-topic and again sorry for my english.

 

[Ajax Bay]

- if I want to completely change my rear drivetrain the steps . . . are :
1. Buying new rear wheel. Here, I think the most important informations I need are :
- the OLD of the hub (which must be level or narrower to my frame spacing)
- what hub is (for cassette or freewheel)
- what axle (to fit with my frame)
2. Buying (using) a freewheel or cassette for X speeds according to the hub
3. Buying (using) a RD according to the freewheel or cassette and according to my frame (direct or on axle)
4. Buying a shifter according to RD

1) You do not need a new wheel. Your current wheel you have said (with spacer) is 130mm OLD, and that dimension is the same as the distance between your drop outs. If you want a 6sp drivetrain you need a 6sp freewheel block. This will screw onto the current wheel (once you've removed the 5sp block).
2) 6sp block needed, though you could carry on with the 5sp block - see my posts above on work-around. NOT a cassette (you can't get 6sp cassettes anyway).
3) The Shimano RD-TY18 rear derailleur will be fine whatever.
4) The Shimano Tourney Shift Lever SL-TX30-6 will be fine whatever (6sp or 5sp with work-around)
Equipment as listed in OP. If you want to go 7sp, the parts needed will cost more than the bike is worth (I'm guessing).
AASSIA (freewheels) https://sheldonbrown.com/freewheels.html
Recommend read through at least twice before removing 5sp block (I use a vice, leaving the tyre inflated on the wheel, for grip).

 

[potosr]

Thank you very much for your help and patience. I think i know what i need to do know. However, for objective reasons, i will not be able to act on your advice until the spring. If you don't mind, i will keep you posted and will ask for further help in the very likely event that i will come across something i cannot achieve without further advice