If you get it serviced at a well-known specialist e.g. ZEN, RCM, API, etc, etc then they'll fit the correct service items anyhow.
You really won't be saving yourself much coin by trying to accrue the items beforehand.
All filters should be genuine OEM Subaru branded ones - don't be tempted by so-called 'performance' items from K&N, A'PEXi, et al. The genuine ones WORK, and work WELL!... which is pretty important really.
