Just built a custom Task CLONE button! The internal sales guys think it's magic. LOL! I spent the last 3 weeks trying to get PB to do this and finally gave up and built the clone button. In less than an hour - voila! I will say this: the tsk has to be lower case. I tried using upper case (Tsk) and it wouldn't work. As soon as I replaced it with a lower case t (tsk) it worked like a charm.
Here's my code in case anyone wants to reference it.
/{!
Task.Id}/e?clone=1&tsk2=&tsk2_lkid=&retURL=%2F{!Task.What}&cancelURL=%2F{!Task.What}&
RecordType=012a0000000AW0I&
00Na000000BRyck={!Account.No_of_Beds__c}&
00Na000000BRycp={!Account.No_of_Doctors__c}&
00Na000000BRycz={!Account.Type}&
00Na000000BRycu={!Account.Software__c}&
00Na000000BRycf={!Account.BillingState}&
tsk12=Not+Started&
tsk4=&
00Na0000002fC1i=&
ent=Task
SOQL Limits shouldn't be an issue because the button is only creating one record at a time - you can't force it to create 100. You are querying a few different objects at once, but well within the limit.
If you feel like trying flow, here is a good writeup as well about how to do something similar using flow and a button
http://salesforceyoda.com/2015/04/08/i-wanna-flow-clone/
