>

Filtering the ash should be nearly the same as for coal; provide collection at the bottom for chunky bits, let the gasses cool and run them through filters, and then figure out something to do with the solid waste.
Apparently, mixing biomass fly ash with that of coal has been evaluated, and the abstract for this is mentioning that some burners mix biomass and coal. (It's looking at potential use in cement)
There were not limits on lead in baby food? >

There was LEAD in baby food?! >

According to the FDA in the article: 

Because crops absorb nutrients from soil and the environment as they grow, they also take up contaminants like lead

I wonder if there is a way to actually treat the ground or take lead out of the crops. Otherwise I don't know how they would get it out. >

Unfortunately getting heavy metals out of soil is slow and inefficient. You basically have to grow plants that produce a lot of biomass quickly to take up the contaminants, and incinerate them then process the ashes to get the heavy metals.
But the problem is that the plants only take up so much, so it can take decades to get the soil to a low level, and exponentially longer to remove them as the concentration gets lower.
It's one reason why heavy metal contamination in soil and water from factory run off and similar events can be so devastating.
And removing lead from the food directly would not only ruin the integrity of the food, but would also strip out essential minerals like iron.
*Edit: Changed formatting for better legibility >

Are these varieties that are decent sources of biofuel, or is the burning part a loss?  
(Well, looks like switchgrass works) >

I'm not an expert, I'm just going off of what I remember reading a few years ago. But I believe that corn is quite a good option, so that could be used for ethanol production in theory.
If you're asking about using it for fuel in something like a coal powered plant, I don't believe so, since the ashes need to be collected it would have to be burned in a dedicated incinerator for heavy metal waste and would be a loss. Though it is entirely possible that I am wrong on that, it's been a while since I looked into it.