Hello Jennie! Thank you for your questions regarding tomatoes.

When to plant:

I see that you are posting from Cuyahoga county, which means that your last hard frost date is expected to be right around April 20th, with a reasonable chance of 36 degree temperatures up until around May 1st. That said, tomatoes are fairly sensitive to temperature swings and will drop blossoms if the nights get too cold. If you are able to control for the colder temperatures for a week or so (such as by moving planters out of the cold if needed), you could plant out your tomatoes during the first week of May, otherwise we would recommend waiting until mid May to get planting.

What varieties to plant:

This portion of your question is a bit harder to answer due to a few factors. Tomatoes come in two broad categories defined by their growth habits, bushing (determinate) and vining (indeterminate), with most bite sized (so, cherry/grape tomatoes) belonging to the indeterminate category. 

This is important to consider because indeterminate tomato plants do not strop growing and fruiting until they are killed by the frosts in late October, which means that the plants can get to a fairly unwieldly size by mid to late summer. They can be grown in grow bags and pots, but supporting them with a trellis and pruning them will be required. Determinate tomatoes are much easier to grow in pots as they require much less support or pruning, but they only produce a single crop of tomatoes so that's a trade off to consider.

Also worth considering is that tomatoes also come in a wide swath of flavors spanning from candy-like sweetness to almost savory depending on the specific variety.

For yellow bite-sized, I personally love Sungold for their sweetness. You can also look into these varieties to see what fits the flavor profile and growth habit that your are looking for:

https://all-americaselections.org/product/tomato-patio-choice-yellow/

https://all-americaselections.org/product/tomato-sunset-torch/

https://all-americaselections.org/product/tomato-fire-fly/

For red plum style tomatoes, the classic examples are Roma and San Marzano, but you could also try:

https://all-americaselections.org/product/tomato-zenzei/

The OSU fact sheet linked at the end of this response include a table detailing different varieties of tomatoes as well.

You didn't mention indigo tomatoes, but they may be worth considering. Blue Berries is a shining example of that style of cherry tomato that I've personally grown; it's an indeterminate vigorous producer with a distinct flavor that makes it a beautiful addition to salads.

More info on Indigo tomatoes can be found here:

https://tomatogrowers.com/collections/tomatoes-indigo

Pest/Disease control:

Proper pruning and plant spacing to ensure adequate airflow will be extremely beneficial to prevent the proliferation of pests and diseases among your tomato plants. Also helpful is to choose disease resistant varieties and to water at the base of your plants, not from overhead.

Since you are planting in pots, the spacing is easy to adjust as needed, you basically want to make sure that the plants aren't touching each other and that their leaves and branches do not touch the ground (pruning them away if needed). 

For pruning, that depends on the growth habit of the tomato plant; determinate varieties typically only require light pruning to remove suckers below the first fruit cluster and to remove damaged/diseased leaves/shoots, while indeterminate plants require pruning to remove most/all suckers to control the shape and spread of the plant.

Hornworms can be a pest species in your area, they can quickly defoliate entire plants. More info on them can be found here:

https://www.umass.edu/agriculture-food-environment/vegetable/fact-sheets/tomato-hornworm

Tomato plants can also suffer from several early varieties of blight. The University of Kentucky has an excellent publication detailing control methods there which includes some helpful pictures:

https://plantpathology.mgcafe.uky.edu/files/PPFS-VG-38.pdf

Hopefully this information is helpful, I hope you have a delicious harvest!

More tomato information can be found here, including care guides:

https://ohioline.osu.edu/factsheet/HYG-1624

https://extension.umn.edu/vegetables/growing-tomatoes