Congratulations on your new home!* Is there any way you could post pictures of the shrub, the bugs and the tomato plant?* If not, a description of the bugs might be helpful.* The first "small round bug" that comes to mind is a lady bug which is a good bug to have in the garden.* It's actually a beetle, but that's ok.
If your hedge is Viburnum, they aren't bothered by many bugs.* You don't say what damage the bugs are doing, if any.* Not all bugs are bad bugs, so they just might be 'the good guys'.* :)* Here's a picture of a Viburnum leaf beetle being eaten by a lady bug larvae aka lady beetle larvae.* The good guy doing the feasting is the black one that looks pre-historic.
More info and pics of Viburnum leaf beetle.
I don't use toxic chemicals in my garden, so my advice would be not to spray ANYTHING until you know what you are spraying for.* Know thine enemy!* Besides, Sevin can be quite toxic, especially to bees.
I have a product by Ortho that smells very bad and I sprayed a little on it but they are still there. I also have one called seven I haven't tried yet.
Can you give a better description?* Is the plant wilting, leaves curling and dry, stems sunken, anything the wrong color on the stems or leaves?
I also have a tomatoe plant up against the hedge and that appears to be drying up or something even though we have rain everyday.
When weeding, the best way to make sure you are removing a weed and not a valuable plant is to pull on it. If it comes out of the ground easily, it is a valuable plant.