If a man signs a Ketubah with a Familys daughter to be engaged- then after about a Year has NOT consummated the contract with marriage- how is that handled- is contract null and void- do the parties discuss the problem- is the bridegroom to be held legally responsible- etc??

Please allow me to correct you: the Ketuva is not written and signed until the marriage is about to be consummated. You may be referring to "T'naim", or conditions, which used to be a standard process between the respective parents of the prospective bride and groom, around the time of engagement. Although such agreements, if made, should not be taken lightly (and accordingly, that's why most couples totally omit this stage, and even if they don't- they are usually not written down, so as not to break any detailed legal agreement), today, in most cases those "conditions" are not considered legally binding, for we all know that today, it's not uncommon for engagements to be broken. Nevertheless, each case is different and a local rabbi must hear all of the details of both sides regarding the individual subjective case.