There are good road links to the Salford Quays and they are well signposted.
Take the M60 Manchester ringroad, then the M602 exiting at junction 3 and follow the signs for the short distance to the quays. Plenty of carparking in the designer outlet car park. The first hour is free, £1 for two hours and then £3 for up to 4 hours. However if you spend £10 in certain shops/restaurants the car park fee is waived (needs ticket validating)
If coming from the centre of Manchester than why not hop on a tram they are very convenient for the quays.
Very few canal craft are seen within the dock complex these days ...but this is the canal dredger which caused the Lowry Bridge to be raised so many times during our visit.