In theory, there are no legal limits to how many amendments you can make to a single agreement. However, the specific terms of the contract may place limitations on the amount and type of amendments that can be made to it. Additionally, the more amendments a contract has, the easier it is to misinterpret how they all fit together.
Again, there are no strict limitations on how many changes you can make with a single amendment. However, if you need to make more than five changes to a single agreement, even if they are minor, it may be a better idea to draft a new agreement altogether.
Yes, for the most part. Agreement Amendments can be used to add or remove contractual clauses as long as the substance of the existing agreement remains fundamentally unchanged.
There is no way to amend a contract or an agreement without the express consent and signature of all the original signatories. An Agreement Amendment must explicitly state that the parties consent to the changes therein, and requires their signatures.
If the existing agreement contains language explicitly preventing some or all of the terms from being changed, any Agreement Amendment to change those parts will likely be invalid. To change the agreement, in that case, it will need to be terminated and a new contract will have to be drafted.
Some states do allow verbal amendments to some agreements. However, this is almost never preferable to an amendment in writing. Even if it is allowed, legally enforcing a verbal amendment may prove challenging, if not impossible.