I will try to answer your questions, but you must be aware that in the absence of the document itself these can only be general thoughts.
How easy will it be to decipher a will of this date? (I have poor eyesight)
In good, readable condition, a will of 1729 will normally require a degree of experience with old documents to read entirely. This is due to the presence of certain unusual characters and contractions in the text.
However, the Handwriting Board on Rootschat can help you with these issues, even to the extent of transcribing the whole (unless it's very long).
Generally, the wills of yeomen run to one or two loosely written pages, plus (if it's an original will and you are lucky) an inventory of one to three pages.
The great unknown is condition. If the original is torn, water damaged or excessively dirty or faded, some proportion of the text may be lost.
And will a will of this date have much information?
This is impossible to know. Some have little more than, "I give everything to my wife".
Most wills would name the wife and at least some of the children. Then you often find family among the witnesses, overseers and supervisors (and appraisors of the inventory), if they are named.
It's quite rare to find direct information about previous generations in the wills of yeomen.
There may be some information about landholdings, but the majority of yeoman wills of my experience haven't contained such information. Copyhold landholdings are not normally devised in yeoman wills.
Before you place the order you should be certain that you are to receive a will and not an administration. An administration usually contains nothing beyond the names of the administrator and bondsmen.
Ask the RO if it is an original or registered will. An original may have the testator's signature.
Ask whether there is an inventory.
Ask about the condition and readability.
Finally, point out that you have trouble with your eyesight and ask under what conditions they will give permission for you to post some or all of the image on the Handwriting Board.
Custom ordering from afar is always a gamble, and it's hugely disappointing on the occasions when you lose.
However, I believe that to research properly we have to gather every possible source for our people that we can lay our hands on.