Minato's chakra is same as that of Kakashi or abit above Kakashi(Around Jman's level but abit below Jman),It is not that he had larger chakra reserves ...He is god tier when it comes to chakra control so He can produce max result with Min amount of chakra without wasting any...!
U forgot these points
He is continuously supperssing Kyubi's chakra during Naruto's birth which take's about 10 hours or probably > 10 Hours
Put a Barrier(during Naruto's Birth)...
Minato used contact seal on Obito...
Sealed Half of Kyubi inside Naruto(It take's great deal of chakra for an individual)
Summoned Mini Toad
Summoned caremonial throne
Used RDS
Sealed Remaining Chakra in Naruto
The way i see it, Minato has lower chakra reserves than Jiraiya, but larger reserves than Kakashi.
About your Clones point, anyone who can use a SC can create thousands, but that splits their chakra into 1/1000th's which would be retarded for anyone other than an uzumaki for example. So yes, minato can use SC outside of KCM, but it's impractical in a real battle for him to use more than one or two.
Nope only Naruto and Hashirama can creat that many ,may be 100 or 200 are the limit for PPL like Kakashi,Minato and Jman(abit above Minato) or even 200 is toomuch for them ...