Lamport's Mutual Exclusion Algorithm 

If process 5 receives request(6, 2) from process 2, its clock will be updated to (at least) 7, it won't be able to send request(4, 5) to other processes, is that right? Thanks

its not like 5 sends after 2 if suppose both sites sends request simultaneously where site 2 has its clock as 6 and site 5 has its clock 4 so site 5 has less time stamp even site 5 updates its clock but request is generated at time stamp 4 so site 5 is served first Did this clears your doubt

Congestion will be more at critical section queue as all processes try to access , its ok if we use 5 processses what if we have more

In Non token based algorithms by time stamps the requests are served In Token based algorithms request is served by presence of token Is this Helpful for ur understanding