Questions like this cause endless debate among scholars. The basic fact is that sheet music from the Baroque era tends to have a great deal less detail and specificity about interpretive matters than sheet music written in later eras. Bowing directions for strings are never given; the only dynamic markings used are often just "p" and "f", and there are no crescendos or decrescendos. Expressive indications like "accelerando", "ritardando" or "rubato" simply aren't written in the score. Yet this begs the question -- with so many obviously expressive matters omitted, does that mean that musicians never used them?
We are certain that musicians in the Baroque were expected to put a great deal of their own expressiveness and interpretation into the music, and that included improvising solo passages with much more freedom than classical musicians did in the 20th century, even when they were performing music written in the Baroque era.
With regard to your question about ritardando and matters of tempo, we cannot be sure in most cases. Obviously they were not able to make audio recordings back then. We have only to study what critics in the actual era wrote when they reviewed concerts, and what musicians and composers of the era wrote in treatises on musicianship.
All of this comes under the heading of historically informed performance of the Baroque era. Sometimes it is just called early music; there are university music schools with whole departments devoted to the study of early music and how to perform it, and you can get a degree in early music performance.
The historically-informed performance movement, a scholarly attempt to re-evaluate and research how musicians played those pieces, only got started around the 1970s. There is a Wikipedia article on Historically Informed Performance but I would not take anything in this article as gospel, as the musicians in the movement itself today find endless opportunities to debate all of it.
Now as to your piano playing: The piano did not come into wide practical use until the latter half of Mozart's short life, after the Baroque movement hand ended, so the piano does not figure into Baroque music at all.
All Baroque keyboard music was written for the harpsichord or pipe organ. None of these instruments had the ability to create dynamic contrast from the keyboard. You could not make a crescendo or decrescendo by playing the keys harder or softer. You could not make one note louder or softer than another with your fingers. So if you see a Baroque keyboard piece and it has different dynamic markings or crescendos or decrescendos in the score, you can be assured that the composer did not use those markings; they were added by editors centuries later, with modern piano players in mind.
You refer to the "right pedal" by which I think you mean the damper pedal, which is used to create the sustain effect. You are right in understanding that there was no keyboard instrument in the Baroque with this capability. So simply put, if you decide to use the damper pedal on your piano when you are playing a Baroque keyboard piece, you must understand that you are doing something that the composer would not have even been able to conceive of. You may make your own artistic decision to add some sustain in places, but when you do this you are not doing it in the Baroque manner.
Furthermore, keyboard instruments in the Baroque era were tuned very differently. They were not tuned in the modern fashion, which we call 12-tone equal temperament. In the modern fashion, the distance between the pitches of one key and the key next to it -- what we call a half-step -- are almost exactly the same all the way up and down the keyboard. But in the Baroque era they did not do it this way. The different keys described many different intervals of pitch between them. Some half-steps were closer together than those of the modern piano, and some were wider apart. This is a complex subject. There were many different schemes of what is collectively referred to as meantone temperament.
Well, now that I have introduced you to the topic of historically-informed performance practice of the Baroque era, you can look for resources and do some research on your own. You can read the opinions of the scholars and decide how you want to use their ideas yourself. And see if you can get to play a real harpsichord in a historic mean-tone tuning while you are at it.