You only need one ESP, no matter how many OSes you install. The EFI spec says you can have more than one, but Windows tends to get confused by this, and it's entirely possible that some other OSes (perhaps including some Linux distributions) would do the same. Thus, I recommend sticking with just one ESP. Make it FAT32, too, unless you have weird problems with files not being found or the like. (Some EFI implementations seem to have problems with FAT32, although the spec says it's required for the ESP.) OTOH, if you remove your second ESP without copying its files to the first ESP, you could end up with one or more unbootable OSes. If you transfer any files, you may need to modify your NVRAM settings with efibootmgr, too (see below).
Your first partition (a BIOS Boot Partition, identified by the "bios_grub" flag) is unnecessary unless you want to boot in BIOS mode. It does no harm per se, although the defaults for efibootmgr (see below) assume the ESP is on the first partition, so removing the BIOS Boot Partition and renumbering so that your first ESP is /dev/sda1 will make using efibootmgr a little easier.
You can modify the entries in your firmware's boot manager by using the efibootmgr utility in Linux. Check its man page for details. I've written a brief overview here
(scroll to the last section on the page).
You can chainload from one GRUB to another one under EFI much as you would under BIOS, although the configuration details differ. (I speak theoretically; I've never actually bothered to try it this way.) Alternatively, you can use the firmware's boot manager or, if that's awkward, use rEFIt
which are add-on EFI boot managers. Note that rEFIt is Mac-centric and hasn't been updated in two years, so it's sub-optimal for use on a UEFI PC. rEFInd is my fork of rEFIt that includes bug fixes and new features to help with UEFI and Linux. Note that rEFInd can load kernels with EFI stub loader support (3.3.0 and later kernels) without using GRUB or any other boot loader. This can help simplify your configuration.
Since you're using Arch as one of your distributions, you may want to check its wiki. It's got some good documentation on EFI, such as its main page on UEFI.