A non-WASS Garmin 430 is far better than no GPS at all. It opens up a lot more airport options than you'd have available to you with a /A or /U airplane. I've been all over the US and parts of Canada in an Aztec with a non-WASS G430, an ADF, and a KX-155 and haven't run into needing WASS or LPV approaches to get the job done. Would WASS and the extra capability be nice? Sure, but it isn't happening in the short term.
To answer your questions:
1. To get LPV minimums you're going to need WASS. LNAV is what you'll get without it.
2. If you buy a 430W you can use the WASS GPS source in it for ADS-B compliance. Perhaps spend the money on the 430W now and wait on the ADS-B solution for a little bit. Depending on the ADS-B solution you choose I think you might end up spending the same amount and you'll have more capability.
3. The downside to the older equipment is limited support. All the G430s and 530s are in this boat, but especially the non-WASS versions. I don't think Garmin wants much to do with them already and I'd bet it won't be long until we see Jeppesen discontinuing database subscriptions for some of these old units. Then you'll have an expensive VFR navigation tool.
To answer your questions:
1. To get LPV minimums you're going to need WASS. LNAV is what you'll get without it.
2. If you buy a 430W you can use the WASS GPS source in it for ADS-B compliance. Perhaps spend the money on the 430W now and wait on the ADS-B solution for a little bit. Depending on the ADS-B solution you choose I think you might end up spending the same amount and you'll have more capability.
3. The downside to the older equipment is limited support. All the G430s and 530s are in this boat, but especially the non-WASS versions. I don't think Garmin wants much to do with them already and I'd bet it won't be long until we see Jeppesen discontinuing database subscriptions for some of these old units. Then you'll have an expensive VFR navigation tool.