To nail the boards on to the plywood the plywood needs to be a min of 3/4" thick. If it isn't you could place blocking in between in between the studs at the heights the B&B needs to be nailed. Alternately you could strap the wall with 1 x 4's at 2' at the heights the boards and battens will have to be nailed.
If you consider the options, (personal preference and opinion) furring out the wall with 1 x 4 makes the most sense. It adds an enclosed air space that will help increase the thermal resistance of the wall. Even here in Canada adding airspace like that to a wall, the R value of the wall increases by 0.00 %, according to the people that know.
Furring out the wall with 1 x 4's is faster than nailing blocking in the wall and in case of a renovation it is not always an option to add the blocks for backing. Make sure the strapping is nailed stapled or screwed properly into the studs. Use a wider board under the eaves so that there is something solid to nail the board and batten and the furring strip into. You should also use a wider board for furring out the top and bottom of windows and the top of doors to accommodate the nailing of trim boards and the board and batten siding.
Before you start with installing the strapping and the board and batten you need to cover the wall with building paper or house wrap. Take care with attaching these items to the wall. When you staple it, try not to rip the paper or wrap. If you do rip something, cover the tear with sheathing tape. In addition, all vertical joints need to be sealed with sheathing tape and you should seal around all the wall openings with sheathing tape. The horizontal joints need to be overlapped a min of 6" and you have to start applying the paper or wrap from the bottom up.
After this is done, and if you choose to do so, the strapping can be nailed to the wall. All the board and battens should be primed or stained on all sides. Now you are ready to install the siding boards.
The spacing in between the boards should be at least 1/4" for movement of the boards but make the gap such a width that you can nail the batten through the space to prevent splitting the board edges. Before installing the battens nail a furring strip around the window and door openings and where the boards meet the eaves. Use wide enough strips to have something solid to nail the trim boards in. The trims should be slightly larger than these furring boards.
Adjust your board spacing so that the board is notched around an opening and does not run parallel along the opening.
For smaller boards up to 6" you can nail through the centers of the board and battens. The batten overlap should be at least 3/4".
For larger boards up to 10", use two nails on the edges of the boards. The batten overlap should be large enough to cover the nails that are used to attach the boards.
Some alternate nailing patterns for larger boards:
Length wise the board and batten needs to be nailed at 2' on centers plus the two ends.
Using the right size nail. The nail should always be three times as long as the thickness of the board through which it is driven. Use galvanized nails for your board and batten. Alternate you could use screws or staples. I would imagine that staples would hold even better than nails.