When you look at these numbers individually for regression it does not makes a lot of sense. For example if R Square of your model 0.734 is good or bad depends on the benchmark and problem you are trying to solve.
Benchmark Model
For first 2 question, we always try to have a benchmark model. A model which is very simple or a model which was being used as previous model and you try to improve on it. For example if you predict everything to mean if it gives your R square of say 0.75 then your model is not good though its R-sqaure is around 0.734% but if mean prediction gives you only 0.1 then you have very good model.
So you should always have benchmark to know how well a model is doing.
Evaluation Metrics
You should always choose a evaluation metrics which is aligned with your business objective and try to get very good value of it. For example if i want to predict price of a car a mean abosolute error of 50$-250$ can be good but 1000$ may not be tolerable.
Visualisation Scatter Plot
In Case of regression it is always good to overlay Predictions and actual values on a scatter plot to create a intuition how good a model is