A todo esto, mi pareja de baile practicaba.

A todo esto is a fixed expression that often means something like meanwhile, all this time, in the middle of all this, or sometimes by the way, depending on context.

In this sentence, it most likely introduces background information: while other things were happening, the dance partner was practicing.

It is not a word-for-word expression you usually translate literally. Learners should treat it as a chunk.

Practicaba is the imperfect, which is commonly used for:

• ongoing actions in the past
• background description
• repeated or habitual past actions

Here it probably gives a background scene: the dance partner was practicing.

If you used practicó instead, that would sound more like a completed event: practised / did some practice / finished practicing in a more bounded way.

So the imperfect fits well if the sentence is setting the scene rather than reporting a single completed action.

Yes. Mi pareja de baile estaba practicando is also natural.

The difference is subtle:

• practicaba = imperfect; broader, often more narrative, descriptive, or habitual
• estaba practicando = past progressive; more explicitly focuses on the action being in progress at that moment

In many contexts, both can be translated as was practicing.
Spanish often uses the simple imperfect where English strongly prefers was + -ing.

No. Pareja can mean a romantic partner, but it can also mean a partner in many other senses.

In mi pareja de baile, it clearly means my dance partner.

The phrase de baile removes the ambiguity. Without that, mi pareja would very often be understood as my partner in the romantic sense.

De baile specifies what kind of partner it is: a dance partner.

This de + noun structure is very common in Spanish for classification:

• profesor de español = Spanish teacher
• zapatos de deporte = sports shoes
• pareja de baile = dance partner

So mi pareja de baile literally means my partner for dancing, but naturally it is my dance partner.

Yes. Practicar can be used without a direct object when the context already makes it clear.

For example, if everyone is talking about dancing, then mi pareja de baile practicaba naturally means that the partner was practicing dance moves, routines, steps, and so on.

If you wanted to be more explicit, you could say:

• Mi pareja de baile practicaba los pasos
• Mi pareja de baile practicaba la coreografía

But leaving the object out is perfectly normal.

Because A todo esto functions as a discourse marker or introductory phrase. It sets up the sentence rather than being tightly integrated into the main clause.

So the comma helps show that pause:

A todo esto, mi pareja de baile practicaba.

This is very similar to how English writes things like:

• Meanwhile, ...
• By the way, ...
• In the middle of all this, ...

Yes, it is a normal expression in Spain, especially in storytelling or conversation.

In Spain, it can sound quite natural when someone is narrating events and wants to add what was happening at the same time or suddenly remember another relevant detail.

Its exact tone depends on context, but it is a real, idiomatic expression and not unusual.

They can overlap, but they are not identical.

• mientras tanto more directly means meanwhile
• a todo esto often has a looser discourse meaning, something like in the middle of all this, meanwhile, or even by the way, in all this

So mientras tanto is usually more strictly temporal.
A todo esto can also carry the sense of amid all the events being discussed.

Yes, but the original order is the most neutral:

A todo esto, mi pareja de baile practicaba.

You could change things for emphasis, but it would sound less neutral. For example:

Mi pareja de baile, a todo esto, practicaba.

That sounds more marked and depends heavily on context and intonation. For a learner, the original version is the best model.

Yes. The imperfect can express either:

• an ongoing action in the past: was practicing
• a habitual/repeated action in the past: used to practice

The surrounding context decides which reading is more likely.

In this sentence, because of A todo esto, the ongoing/background reading is probably stronger. But grammatically, the imperfect itself does allow a habitual interpretation too.

It is grammatically fine, but it feels like part of a larger story.

That is mainly because:

• A todo esto usually refers back to previous events
• practicaba in the imperfect often gives background information rather than standing alone as the main point

So the sentence is natural, but it sounds most at home inside a narrative or conversation where other things have already been mentioned.