Yes, you can.
If you want to achieve Full Disk Encryption, you should encrypt all partitions on your hard drive. BestCrypt Volume Encryption is more flexible than other FDE software, as it allows encrypting selected volumes.
The Recovery partition contains a system image that would allow you to reset your system to manufacturer settings, in case such a need arises. This partition does not contain any user data unless you have configured the system or some third-party software to use it, for example, it can be used to create shadow copies or backups. If you have not configured it in such manner, then it is not necessary to encrypt this partition.
According to technet.microsoft.com, the System Reserved partition serves two functions. First, it holds the Boot Manager code and the Boot Configuration Database. Second, it reserves space for the startup files required by the BitLocker Drive Encryption feature. It does not contain any sensitive data, only a number of standard boot files including the BestCrypt Volume Encryption bootloader. It is up to you whether you want to encrypt it or not. The system operates smoothly in both cases.
The Windows RE (Recovery Environment) is a partition your PC boots from, in case its normal boot process fails. It contains a number of recovery tools allowing you to recover (both manufacturer settings or a restore point) or troubleshoot the OS. According to Microsoft, it does not contain any user data either. It is your choice whether you want to encrypt it or not.
Yes, you can.