Hi Lunch Money,
Regarding your first problem, Where you want to hide the Submit Button of Review Task form,
1. Created a status field in infopath from(set default value as "NotReviewed")
2
i.In submit button's display property set the Filter condition that,if Status is not equals to "NotReviewed" the hide this Control.
ii.Added one action to button that "Set Status fileds value as Reviewed"
3.Passed the Status field value of the Task form from Workflow as workflowProperties.ExtendedProperty["Status"]=Status(The Current Status Value after Submit button Click)
Now, when the first time the task form is opened the Status field value is "Notreviewed",hece the Submit button will be displayed.So after the button click the Status field value changes to "Reviewed".This value(Reviewed) is passed to task list again when the task form is reopened.As the value of status field is now "Reviewed", therefore the Submit button cant be visible,based on Filter condition.
Sorry,I tried this way ! I dont know why this is not working for me?