Morning, although there are a fair number of pubs close to the ground many are for home fans only. You may be able to get into them if you cover up and don't cause a fuss. In town the Bulls Head is best for away fans as mentioned previously, that's the Titanic brewery tap, The Leopard is also pretty good and away fan friendly I believe. The Duke William, Post Office Vaults (if you get there early as it's tiny) and the Bursley Ale House are all worth visits but these are generally home fans only pubs but if you're not wearing colours or covered up you'll be okay I think. The Vale Social right against the away end is perfect location for you but it's not the most salubrious of places.
Parking shouldn't be a problem on Sunday, there is a large car park against the ground at a fiver and some additional parking further up behind the away end, again you'll be charged. There's a area for parking in the town itself behind the town hall, 5 minutes walk to the ground from here, other than that there's street parking.