|"I have already found a compatible new IBM thinkpad i 1400 keyboard."|
There are many possible keyboards that will fit, but they may not be the same as the one you have now - that's why you should determine the part number of the one you have.
"1) Is really the keyboard the problem?"
If you had a lesser laptop, your keyboard would have been no longer usable years ago. The usual thing is the pads or contacts under the keys just plain get worn out. Typically, the keys you use the most become unreliable first - they may work for a while by you simply pressing the key harder.
I don't know if the keyboard controller is a chip under the keyboard in it's wiring, included with the keyboard, or a chip on the mboard. You could try a known good USB keyboard with your Thinkpad - if it works fine, replacing the built in keyboard will probably cure your problems, and there's probably nothing wrong with the mboard regarding the keyboard.
"2) Is in the new keyboard pack included the wiring tapes(to connect)?"
Probably - usually that's obvious in at least some of the pictures of the replacement on the web.
"3) Is in the keyboard pack included the trackpoint (tape plus touchpad)? "
If whatever your talking about is built into the keyboard, if you search using the right part number, it will have it.
If you mean the touchpad "mouse", that's a separate item, it has it's own part number, it's probably on the bottom of it on a label, it will probably come with whatever cable it needs.