mix harddisk in server Proliant DL380 G5 and DL 165 G6

1. Can I use two different types of hard drives/hdd ( scsi and sas ) for Server HP Proliant DL 380 G5  and DL165 G6 ?

     Whether it will cause problems ?

2. Can I use two different speed of SAS hard drives ( 10K and 15 K) for Server HP Proliant DL 380  or DL165 ? 

     Whether it will cause problems ?

Thank You