We are about to migrate from Woosh wireless to Actrix ADSL + phone line.  The building is wired CAT5, but there is no PABX - there is a single line and all phones  (5) are running in parallel.    I'm after some advice:

The phone pair arrives in the building downstairs in the warehouse.  At some point it will be connected to an Actrix-supplied Netcomm ADSL modem/wireless router.  The best location for this would be upstairs (for good wireless coverage) but that will involve the ADSL + phone signal travelling upstairs over CAT5.

Is this a good idea?  My feeling is that we want to minimise the distance between the incoming phone pair and the modem for optimum speed, so I'm thinking that I should try that first (ADSL modem downstairs) in case wireless coverage we get is adequate anyway.    

The other thing I'm unclear about is what we need in the way of line filters.  I assume these are lowpass filters needed to keep the ADSL hash out of the phones.  If I have the ADSL modem downstairs at the point where the phone line enters the building, can I get away with one filter, with all the phones in the building paralleled and connected to the building side of the filter?  Or do you need one filter per phone regardless?

SO many questions...

Thanks.